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- Boron carbide (4)
- Oxide dielectric layers (4)
- Spin crossover (4)
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- Hafnium oxide (2)
- Halocarbon adsorption (2)
- In Se 4 3 (2)
- Lattice vibrations (2)
- Molecular magnets (2)
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- Surface Debye temperature (2)
- Surface-to-bulk core level shift (2)
- Water absorption (2)
- Activation barriers (1)
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- Boron carbide diodes (1)
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Articles 1 - 30 of 284
Full-Text Articles in Physics
What Happens When Transition Metal Trichalcogenides Are Interfaced With Gold?, Archit Dhingra, Dmitri E. Nikonov, Alexey Lipatov, Alexander Sinitskii, Peter Dowben
What Happens When Transition Metal Trichalcogenides Are Interfaced With Gold?, Archit Dhingra, Dmitri E. Nikonov, Alexey Lipatov, Alexander Sinitskii, Peter Dowben
Peter Dowben Publications
Transition metal trichalcogenides (TMTs) are two-dimensional (2D) systems with quasi-one-dimensional (quasi-1D) chains. These 2D materials are less susceptible to undesirable edge defects, which enhances their promise for low-dimensional optical and electronic device applications. However, so far, the performance of 2D devices based on TMTs has been hampered by contact-related issues. Therefore, in this review, a diligent effort has been made to both elucidate and summarize the interfacial interactions between gold and various TMTs, namely, In4Se3, TiS3, ZrS3, HfS3, and HfSe3. X-ray photoemission spectroscopy data, supported by the results …
Voltage Controlled Néel Vector Rotation In Zero Magnetic Field, Ather Mahmood, Will Echtenkamp, Mike Street, Jun Lei Wang, Shi Cao, Takashi Komesu, Peter Dowben, Pratyush Buragohain, Haidong Lu, Alexei Gruverman, Arun Parthasarathy, Shaloo Rakheja, Christian Binek
Voltage Controlled Néel Vector Rotation In Zero Magnetic Field, Ather Mahmood, Will Echtenkamp, Mike Street, Jun Lei Wang, Shi Cao, Takashi Komesu, Peter Dowben, Pratyush Buragohain, Haidong Lu, Alexei Gruverman, Arun Parthasarathy, Shaloo Rakheja, Christian Binek
Peter Dowben Publications
Multi-functional thin films of boron (B) doped Cr2O3 exhibit voltage-controlled and nonvolatile Néel vector reorientation in the absence of an applied magnetic field, H. Toggling of antiferromagnetic states is demonstrated in prototype device structures at CMOS compatible temperatures between 300 and 400 K. The boundary magnetization associated with the Néel vector orientation serves as state variable which is read via magnetoresistive detection in a Pt Hall bar adjacent to the B:Cr2O3 film. Switching of the Hall voltage between zero and non-zero values implies Néel vector rotation by 90 degrees. Combined magnetometry, spin resolved inverse …
Magnetic Field Perturbations To A Soft X-Ray-Activated Fe (Ii) Molecular Spin State Transition, Guanhua Hao, Alpha T. N’Diaye, Thilini K. Ekanayaka, Ashley S. Dale, Xuanyuan Jiang, Esha Mishra, Corbyn Mellinger, Saeed Yazdani, John W. Freeland, Jian Zhang, Ruihua Cheng, Xiaoshan Xu, Peter Dowben
Magnetic Field Perturbations To A Soft X-Ray-Activated Fe (Ii) Molecular Spin State Transition, Guanhua Hao, Alpha T. N’Diaye, Thilini K. Ekanayaka, Ashley S. Dale, Xuanyuan Jiang, Esha Mishra, Corbyn Mellinger, Saeed Yazdani, John W. Freeland, Jian Zhang, Ruihua Cheng, Xiaoshan Xu, Peter Dowben
Peter Dowben Publications
The X-ray-induced spin crossover transition of an Fe (II) molecular thin film in the presence and absence of a magnetic field has been investigated. The thermal activation energy barrier in the soft X-ray activation of the spin crossover transition for [Fe{H2B(pz)2 }2 (bipy)] molecular thin films is reduced in the presence of an applied magnetic field, as measured through X-ray absorption spectroscopy at various temperatures. The influence of a 1.8 T magnetic field is sufficient to cause deviations from the expected exponential spin state transition behavior which is measured in the field free case. We find …
Corrigendum: Surface Termination And Schottky-Barrier Formation Of In4Se3(001) [Semiconductor Science And Technology (2020) 35 (065009) Doi: 10.1088/1361-6641/Ab7e45], Archit Dhingra, Pavlo V. Galiy, Lu Wang, Nataliia S. Vorobeva, Alexey Lipatov, Angel Torres, Taras M. Nenchuk, Simeon J. Gilbert, Alexander Sinitskii, Andrew J. Yost, Wai-Ning Mei, Keisuke Fukutani, Jia Shiang Chen, Peter Dowben
Corrigendum: Surface Termination And Schottky-Barrier Formation Of In4Se3(001) [Semiconductor Science And Technology (2020) 35 (065009) Doi: 10.1088/1361-6641/Ab7e45], Archit Dhingra, Pavlo V. Galiy, Lu Wang, Nataliia S. Vorobeva, Alexey Lipatov, Angel Torres, Taras M. Nenchuk, Simeon J. Gilbert, Alexander Sinitskii, Andrew J. Yost, Wai-Ning Mei, Keisuke Fukutani, Jia Shiang Chen, Peter Dowben
Peter Dowben Publications
Through the description of various surface terminations, the chain direction of In4Se3 in this paper [1] is implied to be in the plane of its surface. Even though the common convention for photoemission spectroscopy is to place z-axis along the surface normal, the axis perpendicular to the growth direction for this indium selenide is the crystallographic a-axis (and not the c-axis) [2–4]. Therefore, in our work the surface of In4Se3 should have been labeled (100), and not (001), to prevent any confusion that may have resulted from a less than conventional index notation. Data availability statement The data that support …
Colossal Intrinsic Exchange Bias From Interfacial Reconstruction In Epitaxial Cofe2 O4/Al2 O3 Thin Films, Detian Yang, Yu Yun, Arjun Subedi, Nicholas E. Rogers, David M. Cornelison, Peter Dowben, Xiaoshan Xu
Colossal Intrinsic Exchange Bias From Interfacial Reconstruction In Epitaxial Cofe2 O4/Al2 O3 Thin Films, Detian Yang, Yu Yun, Arjun Subedi, Nicholas E. Rogers, David M. Cornelison, Peter Dowben, Xiaoshan Xu
Peter Dowben Publications
We have studied the epitaxial CoFe2O4 (111) films grown on Al2O3 (0001) substrates of different thickness at various temperature and discovered colossal intrinsic exchange bias up to 7 ± 2 kOe. X-ray and electron diffraction clearly indicate an interfacial layer about 2 nm of different crystal structure from the “bulk” part of the CoFe2O4 film. The thickness dependence of the exchange bias suggests a hidden antiferromagnetic composition in the interfacial layer that couples to the ferrimagnetic “bulk” part of the CoFe2O4 film as the origin of the exchange …
Correction To "Quantitative Study Of The Energy Changes In Voltage-Controlled Spin Crossover Molecular Thin Films" [The Journal Of Physical Chemistry Letters (2020) 11:19 (8231-8237) Doi: 10.1021/Acs.Jpclett.0c02209], Aaron Mosey, Ashley S. Dale, Guanhua Hao, Alpha N'Diaye, Peter Dowben, Ruihua Cheng
Correction To "Quantitative Study Of The Energy Changes In Voltage-Controlled Spin Crossover Molecular Thin Films" [The Journal Of Physical Chemistry Letters (2020) 11:19 (8231-8237) Doi: 10.1021/Acs.Jpclett.0c02209], Aaron Mosey, Ashley S. Dale, Guanhua Hao, Alpha N'Diaye, Peter Dowben, Ruihua Cheng
Peter Dowben Publications
In our recent publication, Figure 5 was published without adequate due diligence. The correct TOC Abstract graphic and Figure 5 are contained here in this correction. The correct on to off current ratios are in the range of 4 to 5, not 100 and the signal to noise ratios are far less than previously shown.
Nonvolatile Voltage Controlled Molecular Spin‐State Switching For Memory Applications, Thilini K. Ekanayaka, Guanhua Hao, Aaron Mosey, Ashley S. Dale, Xuanyuan Jiang, Andrew J. Yost, Keshab R. Sapkota, George T. Wang, Jian Zhang, Alpha T. N’Diaye, Andrew Marshall, Ruihua Cheng, Azad Naeemi, Xiaoshan Xu, Peter Dowben
Nonvolatile Voltage Controlled Molecular Spin‐State Switching For Memory Applications, Thilini K. Ekanayaka, Guanhua Hao, Aaron Mosey, Ashley S. Dale, Xuanyuan Jiang, Andrew J. Yost, Keshab R. Sapkota, George T. Wang, Jian Zhang, Alpha T. N’Diaye, Andrew Marshall, Ruihua Cheng, Azad Naeemi, Xiaoshan Xu, Peter Dowben
Peter Dowben Publications
Nonvolatile, molecular multiferroic devices have now been demonstrated, but it is worth giving some consideration to the issue of whether such devices could be a competitive alternative for solid-state nonvolatile memory. For the Fe (II) spin crossover complex [Fe{H2B(pz)2}2(bipy)], where pz = tris(pyrazol-1-yl)-borohydride and bipy = 2,20-bipyridine, voltage-controlled isothermal changes in the electronic structure and spin state have been demonstrated and are accompanied by changes in conductance. Higher conductance is seen with [Fe{H2B(pz)2}2(bipy)] in the high spin state, while lower conductance occurs for the low spin state. Plausibly, …
Remote Mesoscopic Signatures Of Induced Magnetic Texture In Graphene, N. Arabchigavkani, R. Somphonsane, H. Ramamoorthy, G. He, J. Nathawat, S. Yin, B. Barut, K. He, M. D. Randle, R. Dixit, K. Sakanashi, N. Aoki, K. Zhang, L. Wang, W. N. Mei, Peter Dowben, J. Fransson, J. P. Bird
Remote Mesoscopic Signatures Of Induced Magnetic Texture In Graphene, N. Arabchigavkani, R. Somphonsane, H. Ramamoorthy, G. He, J. Nathawat, S. Yin, B. Barut, K. He, M. D. Randle, R. Dixit, K. Sakanashi, N. Aoki, K. Zhang, L. Wang, W. N. Mei, Peter Dowben, J. Fransson, J. P. Bird
Peter Dowben Publications
Mesoscopic conductance fluctuations are a ubiquitous signature of phase-coherent transport in small conductors, exhibiting universal character independent of system details. In this Letter, however, we demonstrate a pronounced breakdown of this universality, due to the interplay of local and remote phenomena in transport. Our experiments are performed in a graphene-based interaction-detection geometry, in which an artificial magnetic texture is induced in the graphene layer by covering a portion of it with a micromagnet. When probing conduction at some distance from this region, the strong influence of remote factors is manifested through the appearance of giant conductance fluctuations, with amplitude much …
The Importance Of Frontier Orbital Symmetry In The Adsorption Of Diiodobenzene On Mos2(0001), Prescott E. Evans, Zahra Hooshmand, Talat S. Rahman, Peter Dowben
The Importance Of Frontier Orbital Symmetry In The Adsorption Of Diiodobenzene On Mos2(0001), Prescott E. Evans, Zahra Hooshmand, Talat S. Rahman, Peter Dowben
Peter Dowben Publications
Evidence of a role of frontier orbital symmetry, in the adsorption process of diiodobenzene on MoS2(0001), appears in the huge differences in the rate of adsorption between 1,3-diiodobenzene, 1,2-diiodobenzene and 1,4-diiodobenzene isomers on MoS2. Experiments indicate that the rate of adsorption of 1,3-diiodobenzene on MoS2(0001) is much greater than that of the 1,2-diodobenzene and 1,4-diiodbenzene isomers. As the differences in calculated diiodobenzene isomer-MoS2 system adsorption energies and electron affinities are negligible, frontier orbital symmetry appears to play a significant role in diiodobenzene adsorption on MoS2(0001). The experimental and theory results, in combination, suggest …
Indium Segregation To The Selvedge Of In4Se3 (001), Archit Dhingra, Zoe G. Marzouk, Esha Mishra, Pavlo V. Galiy, Taras M. Nenchuk, Peter Dowben
Indium Segregation To The Selvedge Of In4Se3 (001), Archit Dhingra, Zoe G. Marzouk, Esha Mishra, Pavlo V. Galiy, Taras M. Nenchuk, Peter Dowben
Peter Dowben Publications
Thermal motion of the surface atoms will lead to a decrease in photoemission intensity, while surface segregation may result in an increase of some phostoemission intensities. For In4Se3(001), both effects are seen. The Debye–Waller factor plot, based on the temperature dependent X-ray photoemission spectroscopy (XPS) measurements on In4Se3(001), suggests an upper bound of 203 ± 6 K for the effective Debye temperature, based on the surface component of the In 3d5/2 core-level. Indium is found to segregate to selvedge (subsurface region) of the crystal.
Site Selective Adsorption Of The Spin Crossover Complex Fe(Phen)2(Ncs)2 On Au(111), Sumit Beniwal, Suchetana Sarkar, Felix Baier, Birgit Weber, Peter Dowben, Axel Enders
Site Selective Adsorption Of The Spin Crossover Complex Fe(Phen)2(Ncs)2 On Au(111), Sumit Beniwal, Suchetana Sarkar, Felix Baier, Birgit Weber, Peter Dowben, Axel Enders
Peter Dowben Publications
The iron(II) spin crossover complex Fe(1,10-phenanthroline)2(NCS)2, dubbed Fe-phen, has been studied with scanning tunneling microscopy, after adsorption on the 'herringbone' reconstructed surface of Au(111) for sub-monolayer coverages. The Fe-phen molecules attach, through their NCS-groups, to the Au atoms of the fcc domains of the reconstructed surface only, thereby lifting the herringbone reconstruction. The molecules stack to form 1D chains, which run along the Au[110] directions. Neighboring Fe-phen molecules are separated by approximately 2.65 nm, corresponding to 9 atomic spacings in this direction. The molecular axis, defined by the two phenanthroline groups, is aligned perpendicular to the …
Surface Termination And Schottky-Barrier Formation Of In4Se3(001), Archit Dhingra, Pavlo V. Galiy, Lu Wang, Nataliia S. Vorobeva, Alexey Lipatov, Angel Torres, Taras M. Nenchuk, Simeon J. Gilbert, Alexander Sinitskii, Andrew J. Yost, Wai-Ning Mei, Keisuke Fukutani, Jia Shiang Chen, Peter Dowben
Surface Termination And Schottky-Barrier Formation Of In4Se3(001), Archit Dhingra, Pavlo V. Galiy, Lu Wang, Nataliia S. Vorobeva, Alexey Lipatov, Angel Torres, Taras M. Nenchuk, Simeon J. Gilbert, Alexander Sinitskii, Andrew J. Yost, Wai-Ning Mei, Keisuke Fukutani, Jia Shiang Chen, Peter Dowben
Peter Dowben Publications
The surface termination of In4Se3(001) and the interface of this layered trichalcogenide, with Au, was examined using x-ray photoemission spectroscopy. Low energy electron diffraction indicates that the surface is highly crystalline, but suggests an absence of C2v mirror plane symmetry. The surface termination of the In4Se3(001 is found, by angle-resolved x-ray photoemission spectroscopy, to be In, which is consistent with the observed Schottky barrier formation found with this n-type semiconductor. Transistor measurements confirm earlier results from photoemission, suggesting that In4Se3(001 is an n-type semiconductor, so that Schottky barrier …
The Emergence Of The Local Moment Molecular Spin Transistor, Guanhua Hao, Ruihua Cheng, Peter Dowben
The Emergence Of The Local Moment Molecular Spin Transistor, Guanhua Hao, Ruihua Cheng, Peter Dowben
Peter Dowben Publications
Local moment molecular systems have now been used as the conduction channel in gated spintronics devices, and some of these three terminal devices might even be considered molecular spin transistors. In these systems, the gate voltage can be used to tune the molecular level alignment, while applied magnetic fields have an influence on the spin state, altering the magnetic properties, and providing insights to the magnetic anisotropy. More recently, the use of molecular spin crossover complexes, as the conduction channel, has led to devices that are both nonvolatile and have functionality at higher temperatures. Indeed, some devices have now been …
Probing Ferroelectricity By X-Ray Absorption Spectroscopy In Molecular Crystals, Fujie Tang, Xuanyuan Jiang, Hsin Yu Ko, Jianhang Xu, Mehmet Topsakal, Guanhua Hao, Alpha T. N'Diaye, Peter Dowben, Deyu Lu, Xiaoshan Xu, Xifan Wu
Probing Ferroelectricity By X-Ray Absorption Spectroscopy In Molecular Crystals, Fujie Tang, Xuanyuan Jiang, Hsin Yu Ko, Jianhang Xu, Mehmet Topsakal, Guanhua Hao, Alpha T. N'Diaye, Peter Dowben, Deyu Lu, Xiaoshan Xu, Xifan Wu
Peter Dowben Publications
We carry out X-ray absorption spectroscopy experiment at the oxygen K edge in croconic acid (C5H2O5) crystal as a prototype of ferroelectric organic molecular solid, whose electric polarization is generated by proton transfer. The experimental spectrum is well reproduced by the electron-hole excitation theory simulations from configuration generated by ab initio molecular dynamics simulation. When inversion symmetry is broken in the ferroelectric state, the hydrogen bonding environment on the two bonded molecules become inequivalent. Such a difference is sensitively probed by the bound excitation in the pre-edge, which is strongly localized on the excited …
Detection Of Decoupled Surface And Bulk States In Epitaxial Orthorhombic Sriro3 Thin Films, Prescott E. Evans, Takashi Komesu, Le Zhang, Ding-Fu Shao, Andrew J. Yost, Shiv Kumar, Eike F. Schwier, Kenya Shimada, Evgeny Y. Tsymbal, Xia Hong, P. A. Dowben
Detection Of Decoupled Surface And Bulk States In Epitaxial Orthorhombic Sriro3 Thin Films, Prescott E. Evans, Takashi Komesu, Le Zhang, Ding-Fu Shao, Andrew J. Yost, Shiv Kumar, Eike F. Schwier, Kenya Shimada, Evgeny Y. Tsymbal, Xia Hong, P. A. Dowben
Peter Dowben Publications
We report the experimental evidence of evolving lattice distortion in high quality epitaxial orthorhombic SrIrO3(001) thin films fully strained on (001) SrTiO3 substrates. Angle-resolved X-ray photoemission spectroscopy studies show that the surface layer of 5 nm SrIrO3 films is Sr–O terminated, and subsequent layers recover the semimetallic state, with the band structure consistent with an orthorhombic SrIrO3(001) having the lattice constant of the substrate. While there is no band folding in the experimental band structure, additional super-periodicity is evident in low energy electron diffraction measurements, suggesting the emergence of a transition layer with crystal symmetry evolving from the SrTiO3 substrate …
Manipulation Of The Molecular Spin Crossover Transition Of Fe(H2b(Pz)2)2(Bipy) By Addition Of Polar Molecules, Paulo S. Costa, Guanhua Hao, Alpha T. N'Diaye, Lucie Routaboul, Pierre Braunstein, Xin Zhang, Jian Zhang, Thilini K. Ekanayaka, Qin Yin Shi, V. L. Schlegel, Bernard Doudin, Axel Enders, Peter Dowben
Manipulation Of The Molecular Spin Crossover Transition Of Fe(H2b(Pz)2)2(Bipy) By Addition Of Polar Molecules, Paulo S. Costa, Guanhua Hao, Alpha T. N'Diaye, Lucie Routaboul, Pierre Braunstein, Xin Zhang, Jian Zhang, Thilini K. Ekanayaka, Qin Yin Shi, V. L. Schlegel, Bernard Doudin, Axel Enders, Peter Dowben
Peter Dowben Publications
The addition of various dipolar molecules is shown to affect the temperature dependence of the spin state occupancy of the much studied spin crossover Fe(II) complex, [Fe{H2B(pz)2}2(bipy)] (pz = pyrazol-1-yl, bipy = 2,2′-bipyridine). Specifically, the addition of benzimidazole results in a re-entrant spin crossover transition, i.e. the spin state starts in the mostly low spin state, then high spin state occupancy increases, and finally the high spin state occupancy decreases with increasing temperature. This behavior contrasts with that observed when the highly polar p -benzoquinonemonoimine zwitterion C6H2(..NH2)2(..O)2 was mixed with [Fe{H2B(pz)2}2(bipy)], which resulted in locking [Fe{H2B(pz)2}2(bipy)] largely into a low …
Quantitative Study Of The Energy Changes In Voltage-Controlled Spin Crossover Molecular Thin Films, Aaron Mosey, Ashley S. Dale, Guanhua Hao, Alpha T. N’Diaye, Peter Dowben, Ruihua Cheng
Quantitative Study Of The Energy Changes In Voltage-Controlled Spin Crossover Molecular Thin Films, Aaron Mosey, Ashley S. Dale, Guanhua Hao, Alpha T. N’Diaye, Peter Dowben, Ruihua Cheng
Peter Dowben Publications
Voltage-controlled nonvolatile isothermal spin state switching of a [Fe{H2B(pz)2}2(bipy)] (pz=tris(pyrazol-1-1y)-borohydride, bipy=2,2’-bipyridine) film, more than 40 to 50 molecular layers thick, is possible when it is adsorbed onto a molecular ferroelectric substrate. Accompanying this high spin and low spin state switching, at room temperature, we observe a remarkable change in conductance, thereby allowing not only non-volatile voltage control of the spin state (“write”), but also current sensing of the molecular spin state (“read”). Monte Carlo Ising model simulations of the high spin state occupancy, extracted from x-ray absorption spectroscopy, indicate that the energy difference between the low …
Towards A Strong Spin–Orbit Coupling Magnetoelectric Transistor, Peter Dowben, Christian Binek, Kai Zhang, Lu Wang, Wai-Ning Mei, Jonathan P. Bird, Uttam Singisetti, Xia Hong, Kang L. Wang, Dmitri Nikonov
Towards A Strong Spin–Orbit Coupling Magnetoelectric Transistor, Peter Dowben, Christian Binek, Kai Zhang, Lu Wang, Wai-Ning Mei, Jonathan P. Bird, Uttam Singisetti, Xia Hong, Kang L. Wang, Dmitri Nikonov
Peter Dowben Publications
Here, we outline magnetoelectric (ME) device concepts based on the voltage control of the interface magnetism of an ME antiferromagnet gate dielectric formed on a very thin semiconductor channel with large spin–orbit coupling (SOC). The emphasis of the ME spin field-effect transistors (ME spin FET) is on an antiferromagnet spin–orbit read logic device and a ME spin-FET multiplexer. Both spin-FET schemes exploit the strong SOC in the semiconducting channel materials but remain dependent on the voltage-induced switching of an ME, so that the switching time is limited only by the switching dynamics of the ME. The induced exchange field spin …
Comment On “Electronic Structure Of Mo(1−X)Rex Alloys Studied Through Resonant Photoemission Spectroscopy”, Prescott Evans, Peter A. Dowben
Comment On “Electronic Structure Of Mo(1−X)Rex Alloys Studied Through Resonant Photoemission Spectroscopy”, Prescott Evans, Peter A. Dowben
Peter Dowben Publications
Further analysis of the resonant photoemission data, found within Sundar et al (2016 J. Phys.: Condens. Matter 28 315502), show the intensities do not follow the elemental composition in the Mo1−xRex alloy. Similar trends are observed in the published data for Gd1−xNix alloy films. The analysis of the resonant photoemission intensities suggests that Mo in the Mo1−xRex alloy and Gd in the Gd1−xNix alloy have nearest neighbor bonds to Re and Ni respectively. This means the A–B bond is favored over the average of …
Phase Separation In Lufeo3 Films, Shi Cao, Xiaozhe Zhang, Kishan Sinha, Wenbin Wang, Jian Wang, Peter A. Dowben, Xiaoshan Xu
Phase Separation In Lufeo3 Films, Shi Cao, Xiaozhe Zhang, Kishan Sinha, Wenbin Wang, Jian Wang, Peter A. Dowben, Xiaoshan Xu
Peter Dowben Publications
The structural transition at about 1000°C, from the hexagonal to the orthorhombic phase of LuFeO3, has been investigated in thin films of LuFeO3. Separation of the two structural phases of LuFeO3 occurs on a length scale of micrometer, as visualized in real space using X-ray photoemission electron microscopy. The results are consistent with X-ray diffraction and atomic force microscopy obtained from LuFeO3 thin films undergoing the irreversible structural transition from the hexagonal to the orthorhombic phase of LuFeO3, at elevated temperatures. The sharp phase boundaries between the structural phases are observed to …
Influence Of Steric Hindrance On The Molecular Packing And The Anchoring Of Quinonoid Zwitterions On Gold Surfaces, Minghui Yuan, Iori Tababe, Jean-Marie Bernard- Schaaf, Qin-Yin Shi, Vicki Schlegel, Rachel Schurhammer, Peter A. Dowben, Bernard Doudin, Lucie Routaboul, Pierre Braunstein
Influence Of Steric Hindrance On The Molecular Packing And The Anchoring Of Quinonoid Zwitterions On Gold Surfaces, Minghui Yuan, Iori Tababe, Jean-Marie Bernard- Schaaf, Qin-Yin Shi, Vicki Schlegel, Rachel Schurhammer, Peter A. Dowben, Bernard Doudin, Lucie Routaboul, Pierre Braunstein
Peter Dowben Publications
Driven by the huge potential of engineering the molecular band offset with highly dipolar molecules for improving charge injection into organic electrics, the anchoring of various N-alkyl substituted quinonoid zwitterions of formula C6H2 (···NHR)2 (···O)2 (R = iPr, Cy, CH2CH(Et)CH2CH2CH2CH3,. . .) on gold surfaces is studied. The N–Au interactions result in an orthogonal arrangement of the zwitterions cores with respect to the surface, and stabilize adsorbed compact rows of molecules. IR spectroscopy is used as a straightforward diagnostic tool to validate the presence of …
Low Trap-State Density And Long Carrier Diffusion In Organolead Trihalide Perovskite Single Crystals, Dong Shi, Valerio Adinolfi, Riccardo Comin, Mingjian Yuan, Erkki Alarousu, Andrei Buin, Yin Chen, Sjoerd Hoogland, Alexander Rothenberger, Khabiboulakh Katsiev, Yaroslav B. Losovyj, Xin Zhang, Peter A. Dowben, Omar F. Mohammed, Edward H. Sargent, Osman M. Bakr
Low Trap-State Density And Long Carrier Diffusion In Organolead Trihalide Perovskite Single Crystals, Dong Shi, Valerio Adinolfi, Riccardo Comin, Mingjian Yuan, Erkki Alarousu, Andrei Buin, Yin Chen, Sjoerd Hoogland, Alexander Rothenberger, Khabiboulakh Katsiev, Yaroslav B. Losovyj, Xin Zhang, Peter A. Dowben, Omar F. Mohammed, Edward H. Sargent, Osman M. Bakr
Peter Dowben Publications
The fundamental properties and ultimate performance limits of organolead trihalide MAPbX3 (MA = CH3NH3 +; X = Br– or I–) perovskites remain obscured by extensive disorder in polycrystalline MAPbX3 films. We report an antisolvent vapor-assisted crystallization approach that enables us to create sizable crack-free MAPbX3 single crystals with volumes exceeding 100 cubic millimeters. These large single crystals enabled a detailed characterization of their optical and charge transport characteristics. We observed exceptionally low trap-state densities on the order of 109 to 1010 per cubic centimeter in MAPbX3 single crystals …
Rare Earth Dopant (Nd, Gd, Dy, And Er) Hybridization In Lithium Tetraborate, Tony D. Kelly, James C. Petrosky, John W. Mcclory, Volodymyr T. Adamiv, Yaroslav V. Burak, Bohdan V. Padlyak, Ihor M. Teslyuk, Ning Liu, Lu Wang, Wai-Ning Mei, Peter A. Dowben
Rare Earth Dopant (Nd, Gd, Dy, And Er) Hybridization In Lithium Tetraborate, Tony D. Kelly, James C. Petrosky, John W. Mcclory, Volodymyr T. Adamiv, Yaroslav V. Burak, Bohdan V. Padlyak, Ihor M. Teslyuk, Ning Liu, Lu Wang, Wai-Ning Mei, Peter A. Dowben
Peter Dowben Publications
The four dopants (Nd, Gd, Dy, and Er) substitutionally occupy the Li+ sites in lithium tetra borate (Li2B407: RE) glasses as determined by analysis of the extended X-ray absorption fine structure. The dopants are coordinated by 6-8 oxygen at a distance of 2.3 to 2.5 A. depending on the rare earth. The inverse relationship between the RE-O coordination distance and rare earth (RE) atomic number is consistent with the expected lanthanide atomic radial contraction with increased atomic number. Through analysis of the X-ray absorption near edge structure, the rare earth dopants adopt the RE …
Spin Polarization Asymmetry At The Surface Of Chromia, Shi Cao, Xin Zhang, Ning Wu, A T. N'Diaye, G Chen, A K. Schmid, Xumin Chen, W Echtenkamp, Axel Enders, Christian Binek, Peter A. Dowben
Spin Polarization Asymmetry At The Surface Of Chromia, Shi Cao, Xin Zhang, Ning Wu, A T. N'Diaye, G Chen, A K. Schmid, Xumin Chen, W Echtenkamp, Axel Enders, Christian Binek, Peter A. Dowben
Peter Dowben Publications
We demonstrate boundary spin polarization at the surface of a Cr2O3 single crystal using spin-polarized low-energy electron microscopy (SPLEEM), complementing prior spin polarized photoemission, spin polarized inverse photoemission, and x-ray magnetic circular dichroism photoemission electron microscopy measurements. This work shows that placing a Cr2O3 single crystal into a single domain state will result in net Cr2O3 spin polarization at the boundary, even in the presence of a gold overlayer. There are indications that the SPLEEM contrast for the two polarization states may be different, consistent with scanning tunneling microscopy spectroscopy results …
The Spin State Of A Molecular Adsorbate Driven By The Ferroelectric Substrate Polarization†, Xin Zhang, Tatiana Palamarciuc, Jean-François Létard, Patrick Rosa, Eduardo Vega Lozada, Fernand Torres, Luis G. Rosa, Bernard Doudin, Peter A. Dowben
The Spin State Of A Molecular Adsorbate Driven By The Ferroelectric Substrate Polarization†, Xin Zhang, Tatiana Palamarciuc, Jean-François Létard, Patrick Rosa, Eduardo Vega Lozada, Fernand Torres, Luis G. Rosa, Bernard Doudin, Peter A. Dowben
Peter Dowben Publications
The spin state of [Fe(H2B(pz)2)2(bipy)] thin films is mediated by changes in the electric field at the interface of organic ferroelectric polyvinylidene fluoride with trifluoroethylene (PVDF–TrFE). Signatures of the molecular crossover transition are evident in changes in the unoccupied states and the related shift from diamagnetic to paramagnetic characteristics. This may point the way to the molecular magneto-electric effect on devices.
Increasing The Neel Temperature Of Magnetoelectric Chromia For Voltage-Controlled Spintronics, M Street, W Echtenkamp, Takashi Komesu, Shi Cao, Peter A. Dowben, Christian Binek
Increasing The Neel Temperature Of Magnetoelectric Chromia For Voltage-Controlled Spintronics, M Street, W Echtenkamp, Takashi Komesu, Shi Cao, Peter A. Dowben, Christian Binek
Peter Dowben Publications
Boron doped chromia (Cr2O3) thin films with substitutional doping levels between zero and 3% are grown using pulsed laser deposition in borane background gases. Magnetometry reveals a tunable increase in the Neel temperature of the (0001) textured Cr2BxO3-x thin films at a rate of about 10% with 1% oxygen site substitution preserving a net boundary magnetization. Spin resolved inverse photoemission measured after magnetoelectric annealing in subsequently reversed electric fields evidences voltage-controlled reversal of boundary magnetization and thus magnetoelectricity of Cr2BxO3-x. Conservation of magnetoelectricity far above …
Occupied And Unoccupied Electronic Structure Of Na Doped Mos2(0001), Takashi Komesu, Duy Le, Xin Zhang, Quan Ma, Eike F. Schwier, Yohei Kojima, Mintian Zheng, Hideaki Iwasawa, Kenya Shimada, Masaki Taniguchi, Ludwig Bartels, Talat S. Rahman, Peter A. Dowben
Occupied And Unoccupied Electronic Structure Of Na Doped Mos2(0001), Takashi Komesu, Duy Le, Xin Zhang, Quan Ma, Eike F. Schwier, Yohei Kojima, Mintian Zheng, Hideaki Iwasawa, Kenya Shimada, Masaki Taniguchi, Ludwig Bartels, Talat S. Rahman, Peter A. Dowben
Peter Dowben Publications
The influence of sodium on the band structure of MoS2(0001) and the comparison of the experimental band dispersion with density functional theory show excellent agreement for the occupied states (angle-resolved photoemission) and qualitative agreement for the unoccupied states (inverse photoemission spectroscopy). Na-adsorption leads to charge transfer to the MoS2 surface causing an effect similar to n-type doping of a semiconductor. The MoS2 occupied valence band structure shifts rigidly to greater binding with little change in the occupied state dispersion. Likewise, the unoccupied states shift downward, approaching the Fermi level, yet the amount of the shift for …
The Chromium Site In Doped Glassy Lithium Tetraborate, T D. Kelly, E Echeverria, Sumit Beniwal, V T. Adamiv, Ya V. Burak, Axel Enders, J. C. Petrosky, J W. Mcclory, Peter A. Dowben
The Chromium Site In Doped Glassy Lithium Tetraborate, T D. Kelly, E Echeverria, Sumit Beniwal, V T. Adamiv, Ya V. Burak, Axel Enders, J. C. Petrosky, J W. Mcclory, Peter A. Dowben
Peter Dowben Publications
Using extended X-ray absorption fine structure (EXAFS) spectroscopy, we find that Cr substitutes primarily in the Liþ site as a dopant in lithium tetraborate Li2B4O7 glasses, in this case 98.4Li2B4O7e1.6Cr2O3 or nominally Li1.98Cr0.025B4O7. This strong preference for a single site is nonetheless accompanied by site distortions and some site disorder, helping explain the optical properties of chromium doped Li2B4O7 glasses. The resulting O coordination shell has a contraction of the Cr-O …
Sublattice-Induced Symmetry Breaking And Bandgap Formation In Graphene, Ralph A. Skomski, Peter A. Dowben, M Sky Driver, Jeffery A. Kelber
Sublattice-Induced Symmetry Breaking And Bandgap Formation In Graphene, Ralph A. Skomski, Peter A. Dowben, M Sky Driver, Jeffery A. Kelber
Peter Dowben Publications
A reduction of symmetry from C6v to C3v leads to the opening of a band gap in the otherwise gapless semiconductor graphene. Simple models provide a fairly complete picture of this mechanism for opening a band gap and in fact can be discussed in terms of the tight-binding approximation, accurately resolving the wave-vector space to a very high accuracy. This picture is consistent with experiments that yield a band gap due to A and B graphene-site symmetry breaking due to substrate interactions.
The Unoccupied Electronic Structure Characterization Of Hydrothermally Grown Tho2 Single Crystals, T D. Kelly, J C. Petrosky, D Turner, J W. Mcclory, J M. Mann, J W. Kolis, Xin Zhang, Peter A. Dowben
The Unoccupied Electronic Structure Characterization Of Hydrothermally Grown Tho2 Single Crystals, T D. Kelly, J C. Petrosky, D Turner, J W. Mcclory, J M. Mann, J W. Kolis, Xin Zhang, Peter A. Dowben
Peter Dowben Publications
Single crystals of thorium dioxide ThO2, grown by the hydrothermal growth technique, have been investigated by ultraviolet photoemission spectroscopy (UPS), inverse photoemission spectroscopy (IPES), and L3, M3, M4, and M5 X-ray absorption near edge spectroscopy (XANES). The experimental band gap for large single crystals has been determined to be 6 eV to 7 eV, from UPS and IPES, in line with expectations. The combined UPS and IPES, place the Fermi level near the conduction band minimum, making these crystals n-type, with extensive band tailing, suggesting an optical gap in the region …