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Full-Text Articles in Physics
Enhanced Metallic Properties Of Srruo3 Thin Films Via Kinetically Controlled Pulsed Laser Epitaxy, Justin K. Thompson, J. Nichols, S. Lee, S. Ryee, John H. Gruenewald, John G. Connell, Maryam Souri, J. M. Johnson, J. Hwang, M. J. Han, H. N. Lee, D. -W. Kim, Sung S. Ambrose Seo
Enhanced Metallic Properties Of Srruo3 Thin Films Via Kinetically Controlled Pulsed Laser Epitaxy, Justin K. Thompson, J. Nichols, S. Lee, S. Ryee, John H. Gruenewald, John G. Connell, Maryam Souri, J. M. Johnson, J. Hwang, M. J. Han, H. N. Lee, D. -W. Kim, Sung S. Ambrose Seo
Physics and Astronomy Faculty Publications
Metal electrodes are a universal element of all electronic devices. Conducting SrRuO3 (SRO) epitaxial thin films have been extensively used as electrodes in complex-oxide heterostructures due to good lattice mismatches with perovskite substrates. However, when compared to SRO single crystals, SRO thin films have shown reduced conductivity and Curie temperatures (TC), which can lead to higher Joule heating and energy loss in the devices. Here, we report that high-quality SRO thin films can be synthesized by controlling the plume dynamics and growth rate of pulsed laser epitaxy (PLE) with real-time optical spectroscopic monitoring. The SRO thin …
Magnetoresistance Characteristics In Individual Fe3O4 Single Crystal Nanowire, K. M. Reddy, Nitin P. Padture, Alex Punnoose, Charles Hanna
Magnetoresistance Characteristics In Individual Fe3O4 Single Crystal Nanowire, K. M. Reddy, Nitin P. Padture, Alex Punnoose, Charles Hanna
Physics Faculty Publications and Presentations
We report on the magnetoresistance (MR) and electron transport measurements observed on asingle crystal magnetite nanowire prepared using a hydrothermal synthesis method. High-resolution electron microscopy revealed the single crystal magnetite nanowires with 80–120 nm thickness and up to 8 μm in length. Magnetic measurements showed the typical Verwey transition around 120 K with a 100 Oe room temperature coercivity and 45 emu/g saturationmagnetization, which are comparable to bulk magnetite. Electrical resistance measurements in 5-300 K temperature range were performed by scanning gate voltage and varying appliedmagnetic field. Electrical resistivity of the nanowire was found to be around 5 × …
Electrostatic Force Microscopy And Electrical Isolation Of Etched Few-Layer Graphene Nano-Domains, D. Patrick Hunley, Abhishek Sundararajan, Mathias J. Boland, Douglas R. Strachan
Electrostatic Force Microscopy And Electrical Isolation Of Etched Few-Layer Graphene Nano-Domains, D. Patrick Hunley, Abhishek Sundararajan, Mathias J. Boland, Douglas R. Strachan
Physics and Astronomy Faculty Publications
Nanostructured bi-layer graphene samples formed through catalytic etching are investigated with electrostatic force microscopy. The measurements and supporting computations show a variation in the microscopy signal for different nano-domains that are indicative of changes in capacitive coupling related to their small sizes. Abrupt capacitance variations detected across etch tracks indicates that the nano-domains have strong electrical isolation between them. Comparison of the measurements to a resistor-capacitor model indicates that the resistance between two bi-layer graphene regions separated by an approximately 10 nm wide etch track is greater than about 1×1012 Ω with a corresponding gap resistivity greater than about …
Non-Fermi Liquid Transport And "Universal" Ratios In Quantum Griffiths Phases, David Nozadze, Thomas Vojta
Non-Fermi Liquid Transport And "Universal" Ratios In Quantum Griffiths Phases, David Nozadze, Thomas Vojta
Physics Faculty Research & Creative Works
We use the semi-classical Boltzmann equation to investigate transport properties such as electrical resistivity, thermal resistivity, thermopower, and the Peltier coefficient of disordered metals close to an antiferromagnetic quantum phase transition. In the quantum Griffiths phase, the electrons are scattered by spin-fluctuations in the rare regions. This leads to singular temperature dependencies not just at the quantum critical point, but in the entire Griffiths phase. We show that the resulting non-universal power-laws in transport properties are controlled by the same Griffiths exponent λ which governs the thermodynamics. λ takes the value zero at the quantum critical point and increases throughout …
Stable Highly Conductive Zno Via Reduction Of Zn Vacancies, David C. Look, Timothy C. Droubay, Scott A. Chambers
Stable Highly Conductive Zno Via Reduction Of Zn Vacancies, David C. Look, Timothy C. Droubay, Scott A. Chambers
Physics Faculty Publications
Growth of Ga-doped ZnO by pulsed laser deposition at 200 °C in an ambient of Ar and H2produces a resistivity of 1.5 × 10−4 Ω-cm, stable to 500 °C. The resistivity can be further reduced to 1.2 × 10−4 Ω-cm by annealing on Zn foil, which reduces the compensating Zn-vacancy acceptor concentration NA to 5 × 1019 cm−3, only 3% of the Ga-donor concentration ND of 1.6 × 1021 cm−3, with ND and NA determined from a degenerate mobility theory. The plasmon-resonance wavelength is only 1060 …
Highly Conductive Zno Grown By Pulsed Laser Deposition In Pure Ar, Robin C. Scott, Kevin D. Leedy, Burhan Bayraktaroglu, David C. Look, Yong-Hang Zhang
Highly Conductive Zno Grown By Pulsed Laser Deposition In Pure Ar, Robin C. Scott, Kevin D. Leedy, Burhan Bayraktaroglu, David C. Look, Yong-Hang Zhang
Physics Faculty Publications
Ga-doped ZnO was deposited by pulsed laser deposition at 200 °C on SiO2/Si, Al2O3, or quartz in 10 mTorr of pure Ar. The as-grown, bulk resistivity at 300 K is 1.8×10−4 Ω cm, three-times lower than that of films deposited at 200 °C in 10 mTorr of O2 followed by an anneal at 400 °C in forming gas. Furthermore, depth uniformity of the electrical properties is much improved. Mobility analysis shows that this excellent resistivity is mostly due to an increase in donor concentration, rather than a decrease in acceptor concentration. Optical …
Tunneling Electroresistance In Ferroelectric Tunnel Junctions With A Composite Barrier, M. Ye. Zhuravlev, Yong Wang, S. Maekawa, Evgeny Y. Tsymbal
Tunneling Electroresistance In Ferroelectric Tunnel Junctions With A Composite Barrier, M. Ye. Zhuravlev, Yong Wang, S. Maekawa, Evgeny Y. Tsymbal
Evgeny Tsymbal Publications
Tunneling electroresistance (TER) effect is the change in the electrical resistance of a ferroelectric tunnel junction (FTJ) associated with polarization reversal in the ferroelectric barrier layer. Here we predict that a FTJ with a composite barrier that combines a functional ferroelectric film and a thin layer of a nonpolar dielectric can exhibit a significantly enhanced TER. Due to the change in the electrostatic potential with polarization reversal, the nonpolar dielectric barrier acts as a switch that changes its barrier height from a low to high value. The predicted values of TER are giant and indicate that the resistance of the …
Temperature And Electric Field Dependence Of Conduction In Low-Density Polyethylene, John R. Dennison, Jerilyn Brunson
Temperature And Electric Field Dependence Of Conduction In Low-Density Polyethylene, John R. Dennison, Jerilyn Brunson
All Physics Faculty Publications
A traditional constant voltage conductivity test method was used to measure how the conductivity of highly insulating low-density polyethylene (LDPE) polymer films depends on applied electric field, repeated and prolonged electric field exposure, and sample temperature. The strength of the applied voltage was varied to determine the electric field dependence. At low electric field, the resistivity was measured from cryogenic temperatures to well above the glass transition temperature. Comparisons were made with a variety of models of the conduction mechanisms common in insulators, including transient polarization and diffusion and steady-state thermally activated hopping conductivity and variable range hopping conductivity, to …
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Faculty Publications
No abstract provided.
Competition Between Ferromagnetic Metallic And Paramagnetic Insulating Phases In Manganites, G. Li, H. D. Zhou, S. J. Feng, Xiaojuan Fan, X. G. Li, Z. D. Wang
Competition Between Ferromagnetic Metallic And Paramagnetic Insulating Phases In Manganites, G. Li, H. D. Zhou, S. J. Feng, Xiaojuan Fan, X. G. Li, Z. D. Wang
Physics Faculty Research
La0.67Ca0.33Mn1−xCuxO3(x=0 and 0.15) epitaxial thin films were grown on the (100) LaAlO3 substrates, and the temperature dependence of their resistivity was measured in magnetic fields up to 12 T by a four-probe technique. We found that the competition between the ferromagnetic metallic (FM) and paramagnetic insulating (PI) phases plays an important role in the observed colossal magnetoresistance(CMR) effect. Based on a scenario that the doped manganites approximately consist of phase-separated FM and PI regions, a simple phenomenological model was proposed to describe the CMR effect. Using this model, we …