Yuyi Xue

Field-induced resistive switching in metal-oxide interfaces

We investigate the polarity-dependent field-induced resistive switching phenomenon driven by electric pulses in perovskite oxides. Our data show that the switching is a common occurrence restricted to an interfacial layer between a deposited metal electrode and the oxide. We determine through impedance spectroscopy that the interfacial layer is no thicker than 10nm and that the switch is accompanied by a small capacitance increase associated with charge accumulation. Based on interfacial I–V characterization and measurement of the temperature dependence of the resistance, we propose that a field-created crystalline defect mechanism, which is controllable for devices, drives the switch.

Unusual superconducting state at 49 K in electron-doped CaFe2As2 at ambient pressure

We report the detection of unusual superconductivity up to 49 K in single crystalline CaFe2As2 via electron-doping by partial replacement of Ca by rare-earth. The superconducting transition observed suggests the possible existence of two phases: one starting at 49 K, which has a low critical field < 4 Oe, and the other at 21 K, with a much higher critical field > 5 T. Our observations are in strong contrast to previous reports of doping or pressurizing layered compounds AeFe2As2 (or Ae122), where Ae = Ca, Sr, or Ba. In Ae122, hole-doping has been previously observed to generate superconductivity with a transition temperature (Tc) only up to 38 K and pressurization has been reported to produce superconductivity with a Tc up to 30 K. The unusual 49 K phase detected will be discussed.

Mechanism and scalability in resistive switching of metal-Pr0.7Ca0.3MnO3 interface

The polarity-dependent resistive switching across metal-Pr0.7Ca0.3MnO3 interfaces is investigated. The data suggest that shallow defects in the interface dominate the switching. Their density and fluctuation, therefore, will ultimately limit the device size. While the defects generated/annihilated by the pulses and the associated carrier depletion seem to play the major role at lower defect density, the defect correlations and their associated hopping ranges appear to dominate at higher defect density. Therefore, the switching characteristics, especially the size scalability, may be altered through interface treatments.

Effects of material processing in high temperature superconducting magnetic bearings

A study of the levitation forces related to superconducting bearing design was conducted on free‐sintered and melt‐textured Y1Ba2Cu3O7−δ(YBCO) materials. Comparisons were made between free sintered, variously oriented, and randomly oriented melt‐textured materials. Magnetic force measurements were also conducted on oriented YBCO before and after neutron irradiation. A magnetic bearing of new design utilizing the phenomenon of flux pinning was then fabricated using melt‐textured YBCO with permanent magnets and a speed of 135 000 rpm was achieved. Rotational dissipation and magnetic stiffness measurements were performed on the bearing prototype.

High-pressure and doping studies of the superconducting antiperovskite SrPt3P

We report the results of our investigation of

Synthesis, Structure, and Superconductivity in the New-Structure-Type Compound: SrPt6P2

{\mathrm{SrPt}}_{3}\mathrm{P}

General mechanism for negative capacitance phenomena

, a recently discovered strong-coupling superconductor with

Electric-field-induced submicrosecond resistive switching

{T}_{c}=8.4

Disorder-induced bulk superconductivity in ZrTe3single crystals via growth control

K, by application of high physical pressure and by chemical doping. We study hole-doped

Kinetics and relaxation of electroresistance in transition metal oxides: Model for resistive switching

{\mathrm{SrPt}}_{3}\mathrm{P}