The Superconductivity in Bi-Doped BaFeAs Single Crystals.

We have successfully synthesized a series of Bi-doped BaFeAs high-quality single crystals for the first time. X-ray diffraction (XRD) patterns show an expansion of lattice parameter with Bi doping, indicating a negative pressure effect. By investigating the resistivity, a Fermi liquid (FL) to non-Fermi liquid (NFL) crossover is observed from normal state to antiferromagnetic order state, accompanied by three superconducting transitions labeled as SC I, SC II and SC III, which are supposed to be induced by three superconducting realms with various Bi concentrations.

Evidence for unconventional superconductivity and nontrivial topology in PdTe.

PdTe is a superconductor with T ~ 4.25 K. Recently, evidence for bulk-nodal and surface-nodeless gap features has been reported in PdTe.

Quantum Phase Transition of Correlated Iron-Based Superconductivity in LiFe_{1-x}Co_{x}As.

The interplay between unconventional Cooper pairing and quantum states associated with atomic scale defects is a frontier of research with many open questions. So far, only a few of the high-temperature superconductors allow this intricate physics to be studied in a widely tunable way. We use scanning tunneling microscopy to image the electronic impact of Co atoms on the ground state of the LiFe_{1-x}Co_{x}As system.

Low-Dimensional Magnetic Semimetal CrAlSe.

While exploring novel magnetic semiconductors, the new phase CrAlSe was discovered and characterized by both structural and physical properties. CrAlSe was found to crystallize into orthorhombic CrGeTe-type structure with space group (no. 62).

CrGaSe: A Quasi-Two-Dimensional Magnetic Semiconductor.

We present a novel magnetic semiconductor, CrGaSe, synthesized by partially replacing magnetic Cr in antiferromagnetic CrSe with nonmagnetic Ga. The crystal structure of CrGaSe was determined by both powder and single-crystal X-ray diffraction. The title compound crystallizes in a monoclinic structure with space group C2/ m (No.

Mn-induced Ferromagnetic Semiconducting Behavior with Linear Negative Magnetoresistance in Sr(RuMn)O Single Crystals.

Triple-layered SrRuO is a unique ferromagnet with the central RuO layer behaving differently from two outer layers both crystallographically and magnetically. We report that the partial substitution of Ru by smaller Mn gives rise to modification in crystal structure, electronic and magnetic properties of Sr(RuMn)O. Through the single crystal X-ray diffraction refinement, we find that (Ru/Mn)O octahedral rotation is no longer detectable at x ≥ 0.

Pt-Bi Antibonding Interaction: The Key Factor for Superconductivity in Monoclinic BaPtBi.

In the search for superconductivity in a BaAuSb-type monoclinic structure, we have successfully synthesized the new compound BaPtBi, which crystallizes in the space group P2/m (No. 11; Pearson symbol mP10) according to a combination of powder and single-crystal X-ray diffraction and scanning electron microscopy. A sharp electrical resistivity drop and large diamagnetic magnetization below 2.

Magnetic moment evolution and spin freezing in doped BaFeAs.

Fe-K X-ray emission spectroscopy measurements reveal an asymmetric doping dependence of the magnetic moments μ in electron- and hole-doped BaFeAs. At low temperature, μ is nearly constant in hole-doped samples, whereas it decreases upon electron doping. Increasing temperature substantially enhances μ in the hole-doped region, which is naturally explained by the theoretically predicted crossover into a spin-frozen state.

Orbital Selective Spin Excitations and their Impact on Superconductivity of LiFe_{1-x}Co_{x}As.

We use neutron scattering to study spin excitations in single crystals of LiFe_{0.88}Co_{0.12}As, which is located near the boundary of the superconducting phase of LiFe_{1-x}Co_{x}As and exhibits non-Fermi-liquid behavior indicative of a quantum critical point.