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Articles 1 - 10 of 10
Full-Text Articles in Physics
Surface Versus Bulk State Transitions In Inkjet-Printed All-Inorganic Perovskite Quantum Dot Films, Thilini K. Ekanayaka, Dylan Richmond, Mason Mccormick, Shashank R. Nandyala, Halle C. Helfrich, Alexander Sinitskii, Jon M. Pikal, Carolina C. Ilie, Peter A. Dowben, Andrew J. Yost
Surface Versus Bulk State Transitions In Inkjet-Printed All-Inorganic Perovskite Quantum Dot Films, Thilini K. Ekanayaka, Dylan Richmond, Mason Mccormick, Shashank R. Nandyala, Halle C. Helfrich, Alexander Sinitskii, Jon M. Pikal, Carolina C. Ilie, Peter A. Dowben, Andrew J. Yost
Department of Physics and Astronomy: Faculty Publications
The anion exchange of the halides, Br and I, is demonstrated through the direct mixing of two pure perovskite quantum dot solutions, CsPbBr3 and CsPbI3, and is shown to be both facile and result in a completely alloyed single phase mixed halide perovskite. Anion exchange is also observed in an interlayer printing method utilizing the pure, unalloyed perovskite solutions and a commercial inkjet printer. The halide exchange was confirmed by optical absorption spectroscopy, photoluminescent spectroscopy, X-ray diffraction, and X-ray photoemission spectroscopy characterization and indicates that alloying is thermodynamically favorable, while the formation of a clustered alloy is …
Unconventional Josephson Junctions With Topological Kondo Insulator Weak Links, Xuecheng Ye, Jacob Cook, Erik D. Huemiller, Aaron D. K. Finck, P. K. Ghaemi, Thomas Vojta, For Full List Of Authors, See Publisher's Website.
Unconventional Josephson Junctions With Topological Kondo Insulator Weak Links, Xuecheng Ye, Jacob Cook, Erik D. Huemiller, Aaron D. K. Finck, P. K. Ghaemi, Thomas Vojta, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
Proximity-induced superconductivity in three-dimensional (3D) topological insulators forms a new quantum phase of matter and accommodates exotic quasiparticles such as Majorana bound states. One of the biggest drawbacks of the commonly studied 3D topological insulators is the presence of conducting bulk that obscures both surface states and low energy bound states. Introducing superconductivity in topological Kondo insulators such as SmB6, however, is promising due to their true insulating bulk at low temperatures. In this work, we develop an unconventional Josephson junction by coupling superconducting Nb leads to the surface states of a SmB6 crystal. We observe a robust critical current …
Ferromagnetism Of Magnetically Doped Topological Insulators In Crxbi2− Xte3 Thin Films, Yan Ni, Z. Zhang, Ikenna C. Nlebedim, M. Ravi Hadimani, Gary L. Tuttle, David C. Jiles
Ferromagnetism Of Magnetically Doped Topological Insulators In Crxbi2− Xte3 Thin Films, Yan Ni, Z. Zhang, Ikenna C. Nlebedim, M. Ravi Hadimani, Gary L. Tuttle, David C. Jiles
Gary Tuttle
We investigated the effect of magnetic doping on magnetic and transport properties of Bi2Te3thin films. CrxBi2−xTe3 thin films with x = 0.03, 0.14, and 0.29 were grown epitaxially on mica substrate with low surface roughness (∼0.4 nm). It is found that Cr is an electron acceptor in Bi2Te3 and increases the magnetization of CrxBi2−xTe3. When x = 0.14 and 0.29,ferromagnetism appears in CrxBi2−xTe3 thin films, where anomalous Hall effect and weak localization of magnetoconductance were observed. The Curie temperature, coercivity, and remnant Hall resistance of thin films increase with increasing Cr concentration. The Arrott-Noakes plot demonstrates that the critical mechanism …
Path Integral Study Of The Correlated Electronic States Of Na4–Na6, Randall W. Hall
Path Integral Study Of The Correlated Electronic States Of Na4–Na6, Randall W. Hall
Randall W. Hall
Feynman’s path integral formulation of quantum mechanics is used to study the correlated electronic states of Na4–Na6. Two types of simulations are performed: in the first, the nuclei are allowed to move at finite temperature in order to find the most stable geometries. In agreement with previous calculations, we find that planar structures are the most stable and that there is significant vibrational amplitude at finite temperatures, indicating that the Born–Oppenheimer surface is relatively flat. In the second type of simulation, the nuclei are held fixed at symmetric and asymmetric geometries and the correlated electron density is found. Our results …
Magnetism Of Zn-Doped Sno2: Role Of Surfaces, Pushpa Raghani, Balaji Ramanujam
Magnetism Of Zn-Doped Sno2: Role Of Surfaces, Pushpa Raghani, Balaji Ramanujam
Physics Faculty Publications and Presentations
Surface effects on the magnetization of Zn-doped SnO2 are investigated using first principles method. Magnetic behavior of Zn-doped bulk and highest and lowest energy surfaces—(001) and (110), respectively, are investigated in presence and absence of other intrinsic defects. The Zn-doped (110) and (001) surfaces of SnO2 show appreciable increase in the magnetic moment (MM) compared to Zn-doped bulk SnO2. Formation energies of Zn defects on both the surfaces are found to be lower than those in bulk SnO2. Zn doping favors the formation of oxygen vacancies. The density of states analysis on the Zn-doped …
Magnetism Of Zn-Doped Sno2: Role Of Surfaces, Pushpa Raghani, Balaji Ramanujam
Magnetism Of Zn-Doped Sno2: Role Of Surfaces, Pushpa Raghani, Balaji Ramanujam
Pushpa Raghani
Surface effects on the magnetization of Zn-doped SnO2 are investigated using first principles method. Magnetic behavior of Zn-doped bulk and highest and lowest energy surfaces—(001) and (110), respectively, are investigated in presence and absence of other intrinsic defects. The Zn-doped (110) and (001) surfaces of SnO2 show appreciable increase in the magnetic moment (MM) compared to Zn-doped bulk SnO2. Formation energies of Zn defects on both the surfaces are found to be lower than those in bulk SnO2. Zn doping favors the formation of oxygen vacancies. The density of states analysis on the Zn-doped (110) surface reveals that the spin …
Reflectance Anisotropy Of Gd5si2ge2 And Tb5si2.2ge1.8, S. J. Lee, Joong Mok Park, J. E. Snyder, David C. Jiles, Deborah L. Schlagel, Thomas A. Lograsso, A. O. Pecharsky, David W. Lynch
Reflectance Anisotropy Of Gd5si2ge2 And Tb5si2.2ge1.8, S. J. Lee, Joong Mok Park, J. E. Snyder, David C. Jiles, Deborah L. Schlagel, Thomas A. Lograsso, A. O. Pecharsky, David W. Lynch
Professor David Lynch
Reflectance difference (RD) spectra for the a–b plane of the single crystals of Gd5Si2Ge2and b–c planes of Gd5Si2Ge2 and Tb5Si2.2Ge1.8 were obtained in the photon energy range of 1.5–5.5 eV. Several peaks were observed for these crystals in the measured spectrum range. Similar features were observed in the RD spectra for the b–c planes ofGd5Si2Ge2 and Tb5Si2.2Ge1.8, while different features were observed for the a–b plane and b–c plane of Gd5Si2Ge2. The RD spectra for the crystals arise not only from the surface anisotropy but also from the bulk anisotropy due to the monoclinic structure of the bulk crystal.
Surface States And Angle-Resolved Photoemission Spectra From Nd₂₋ₓceₓcuo₄, M. Lindroos, A. Bansil
Surface States And Angle-Resolved Photoemission Spectra From Nd₂₋ₓceₓcuo₄, M. Lindroos, A. Bansil
Arun Bansil
By carrying out first-principles angle-resolved photoemission (ARPES) computations within the local-density-approximation-based band theory framework, we predict the existence of surface states on the (001) surface of the superconductor Nd₂₋ₓCeₓCuO₄ (NCCO). Two surface state bands are identified in the vicinity of the Fermi energy. The associated states possess quite different characteristics in terms of their binding energy, dispersion with k∥, and the polarization and photon energy dependence. Our theoretical predictions offer new insight into the existing ARPES data on NCCO with which they are consistent.
Photoluminescence Properties Of Silicon Quantum-Well Layers, Peter N. Saeta, A. C. Gallagher
Photoluminescence Properties Of Silicon Quantum-Well Layers, Peter N. Saeta, A. C. Gallagher
All HMC Faculty Publications and Research
Nanometer-scale crystal silicon films surrounded by SiO2 were prepared by oxidizing silicon-on-insulator substrates prepared from SIMOX (separation by implantation of oxygen) and crystallized hydrogenated amorphous silicon films. Average silicon layer thickness was determined from reflection spectra. When sufficiently thin (<2 >nm), all layers emitted red photoluminescence under blue and UV cw excitation, with a spectrum that did not depend on the mean layer thickness. The spectrum was roughly Gaussian with a peak energy of 1.65 eV, which is lower than for most porous silicon spectra. The time scale for the luminescence decay was ~35 μs at room temperature and …
Path Integral Study Of The Correlated Electronic States Of Na4–Na6, Randall W. Hall
Path Integral Study Of The Correlated Electronic States Of Na4–Na6, Randall W. Hall
Collected Faculty and Staff Scholarship
Feynman’s path integral formulation of quantum mechanics is used to study the correlated electronic states of Na4–Na6. Two types of simulations are performed: in the first, the nuclei are allowed to move at finite temperature in order to find the most stable geometries. In agreement with previous calculations, we find that planar structures are the most stable and that there is significant vibrational amplitude at finite temperatures, indicating that the Born–Oppenheimer surface is relatively flat. In the second type of simulation, the nuclei are held fixed at symmetric and asymmetric geometries and the correlated electron density is found. Our results …