arXiv subjects

X. C. Wang

Publications and source records attributed to X. C. Wang.

42 records · Page 3Linked to original sources

arXiv2011

Pressure induced Superconductivity in Topological Compound Bi2Te3

Bi2Te3 compound has been theoretically predicted (1) to be a topological insulator, and its topologically non-trivial surface state with a single Dirac cone has been observed in photoemission experiments (2). Here we report that superconductivity (Tc^~3K) can be induced in Bi2Te3 as-grown single crystal (with hole-carriers) via pressure. The first-principles calculations show that the electronic structure under pressure remains to be topologically nontrivial, and the Dirac-type surface states can be well distinguished from bulk states at corresponding Fermi level. The proximity effect between superconducting bulk states and Dirac-type surface state could generate Majorana fermions on the surface. We also discuss the possibility that the bulk state could be a topological superconductor.

cond-mat.supr-con↗

arXiv2010

$^{75}$As NQR and NMR studies of superconductivity and electron correlations in iron arsenide Li$_{x}$FeAs

We report the $^{75}$As-NQR and NMR studies on the iron arsenide superconductor Li$_{x}$FeAs with $T_{\rm c} \sim 17$ K. The spin lattice relaxation rate, $1/T_{1}$, decreases below $T_{\rm c}$ without a coherence peak, and can be fitted by gaps with s$^{\pm}$-wave symmetry in the presence of impurity scattering. In the normal state, both $1/T_{1}T$ and the Knight shift decrease with decreasing temperature but become constant below $T \leq 50 K$. Estimate of the Korringa ratio shows that the spin correlations are weaker than that in other families of iron arsenides, which may account for the lower $T_{\rm c}$ in this material.

cond-mat.supr-con↗

arXiv2010

Temperature - pressure phase diagram of the superconducting iron pnictide LiFeP

Electrical-resistivity and magnetic-susceptibility measurements under hydrostatic pressure up to p = 2.75 GPa have been performed on superconducting LiFeP. A broad superconducting (SC) region exists in the temperature - pressure (T-p) phase diagram. No indications for a spin-density-wave transition have been found, but an enhanced resistivity coefficient at low pressures hints at the presence of magnetic fluctuations. Our results show that the superconducting state in LiFeP is more robust than in the isostructural and isoelectronic LiFeAs. We suggest that this finding is related to the nearly regular [FeP_4] tetrahedron in LiFeP.

cond-mat.supr-con↗

arXiv2009

Superconductivity at 31 K in 111 type iron arsenide superconductor NaxFeAs induced by pressure

The effect of pressure on superconductivity of 111 type NaxFeAs is investigated through temperature dependent electrical resistance measurement in a diamond anvil cell. The superconducting transition temperature (Tc) increases from 26 K to a maximum 31 K as the pressure increases from ambient to 3 GPa. Further increasing pressure suppresses Tc drastically. The behavior of pressure tuned Tc in NaxFeAs is much different from that in LixFeAs, although they have the same Cu2Sb type structure

cond-mat.supr-con↗

arXiv2009

A new 111 type iron pnictide superconductor LiFeP

A new iron pnictide LiFeP superconductor was found. The compound crystallizes into a Cu2Sb structure containing an FeP layer showing superconductivity with maximum Tc of 6K. This is the first 111 type iron pnictide superconductor containing no arsenic. The new superconductor is featured with itinerant behavior at normal state that could helpful to understand the novel superconducting mechanism of iron pnictide compounds.

cond-mat.supr-con↗

arXiv2008

The superconductivity at 18 K in LiFeAs system

A new iron arsenide superconducting system LiFeAs was found that crystallizes into a tetragonal structure with space group P4/nmm. The superconductivity with Tc up to 18 K was observed in the compounds. This simple 111 type layered iron arsenide superconductor can be viewed as an analogue of the infinite layer structure of copper oxides.

cond-mat.supr-con↗