Shile Zhang

Superconductivity of the topological insulator Bi2Se3 at high pressure

The pressure-induced superconductivity and structural evolution of Bi2Se3 single crystals are studied. The emergence of superconductivity at an onset transition temperature (Tc) of about 4.4 K is observed at around 12 GPa. Tc increases rapidly to a maximum of 8.2 K at 17.2 GPa, decreases to around 6.5 K at 23 GPa, and then remains almost constant with further increases in pressure. Variations in Tc with respect to pressure are closely related to the carrier density, which increases by over two orders of magnitude from 2 to 23 GPa. High-pressure synchrotron radiation measurements reveal structural transitions at around 12, 20, and above 29 GPa. A phase diagram of superconductivity versus pressure is also constructed.

Disorder-induced orbital glass state in FeCr2S4

The effect of disorder on the orbital state in the spinel FeCr2S4 has been investigated with the substitution of Cr by Al, Ga, and Fe, respectively. For polycrystalline FeCr2S4, being related to the orbital-ordering transition around 9 K, the temperature dependence of magnetization shows a step-like transition, and the specific heat displays a well-defined λ-type anomaly correspondingly. However for single-crystal and doped FeCr2S4 samples, the step-like transition in magnetization disappears, and the λ-type anomaly of specific heat is replaced by a broad hump. Moreover, the specific heat obeys a T2-dependence at temperatures below 2 K, suggesting the formation of the orbital glass state in these samples. Consistently with different orbital states, the resistivity at low temperature can be better fitted with a thermally activated model for the polycrystalline FeCr2S4 sample, and better described by Motts variable-range hopping expression for the others. All these results imply that the disorder induces orbital glass state in FeCr2S4.

Quantitative determination of Eliashberg function and evidence of strong electron coupling with multiple phonon modes in heavily overdoped (Bi,Pb)(2)Sr2CuO6+delta

It is known that the parity of a reflection amplitude can either be even or odd under a mirror operation. Up to now to our knowledge, all the parities of a reflection amplitude in the one-mode energy region have been even under a mirror operation. In this paper, we give an example of odd parity for Andreev reflection (AR) in a three-terminal graphene-supercondutor hybrid system. We found that the parity is even for the Andreev retroreflection and odd for specular Andreev reflection (SAR). We attribute this remarkable phenomenon to the distinct topology of the band structure of graphene and the specular Andreev reflection involving two energy bands with different parity symmetry. As a result of the odd parity of SAR, the SAR probability of a four-terminal system with two superconducting leads (two reflection interfaces) can be 0 even when the system is asymmetric due to the quantum interference of two ARs.

Spin-phonon coupling probed by infrared transmission spectroscopy in the double perovskite Ba2YMoO6

In this work, we investigate the local structural distortion of the double perovskite Ba

Coexistence of incommensurate and commensurate spiral orders and pressure effect on polycrystalline CoCr2O4

_2

Doping effects on the magnetic properties of La0.5Ba0.5Co1−xTixO3

YMoO

The role of Ru5+ in increasing TC of Cr-doped SrRuO3 system

_6

Magnetic states of BaFe2-xCoxAs2 single crystals Magnetization and electron spin resonance study

by means of infrared transmission spectroscopy. At 300 K, three bands are observed at

Nonzero electric polarization and four magnetoelectric states at zero magnetic field in Cr-doped Y-type hexaferrite

\sim

A new 111 type iron pnictide superconductor LiFeP

255.1 cm