Since the three dimensional (3D) Dirac semi-metal Cd 3 As 2 exists close to topological phase boundaries, in principle it should be possible to drive it into exotic new phases, like topological superconductors, by breaking certain symmetries. Here we show that the mesoscopic point-contacts between silver (Ag) and Cd 3 As 2 exhibit superconductivity up to a critical temperature (onset) of 6 K while neither Cd 3 As 2 nor Ag are superconductors. A gap amplitude of 6.5 meV is measured spectroscopically in this phase that varies weakly with temperature and survives up to a remarkably high temperature of 13 K indicating the presence of a robust normal-state pseudogap. The observations indicate the emergence of a new unconventional superconducting phase that exists only in a quantum mechanically confined region under a point-contact between a Dirac semi-metal and a normal metal. * These authors contributed equally to the work † ashok@chemistry.iitd.ac.in ‡ goutam@iisermohali.ac.in 1 arXiv:1410.2072v1 [cond-mat.supr-con]

Crystal structure and properties of a new member of oxy-bismuth-sulfide family SmO 0.5 F 0.

Topological materials have recently attracted considerable attention among materials scientists as their properties are predicted to be protected against perturbations such as lattice distortion and chemical substitution. However, any experimental proof of such robustness is still lacking. In this study, we experimentally demonstrate that the topological properties of the ferromagnetic kagomé compound Co3Sn2S2 are preserved upon Ni substitution. We systematically vary the Ni content in Co3Sn2S2 single crystals and study their magnetic and anomalous transport properties. For the intermediate Ni substitution, we observe a remarkable increase in the coercive field while still maintaining significant anomalous Hall conductivity. The large anomalous Hall conductivity of these compounds is intrinsic, consistent with first-principle calculations, which proves its topological origin. Our results can guide further studies on the chemical tuning of topological materials for better understanding.

We have synthesized CuFeAs, a new iron-pnictide compound with a layered tetragonal Cu2Sb type structure (space group P4/nmm: a = b = 3.7442(2) {\AA} and c = 5.8925(4) {\AA}) that is identical to that of 111-type iron-based superconductors. Our measurements suggest that in low applied magnetic field it undergoes an antiferromagnetic transition below TN ~ 9 K. When compared with the ground state of CuFeSb, recently reported 111-type ferromagnetic material (TC ~ 375 K), it has important implication with regard to the nature of Fe-Fe magnetic interaction in Fe-As materials. CuFeAs does not exhibit superconductivity down to 2 K.Comment: 8 pages, 5 figure

We have investigated the effect of La doping and high pressure on superconducting properties of EuBiS 2 F which is a newly discovered superconducting material (T c ~ 0.3 K) [Phys. Rev. B 90, 064518 (2014)]. An enhancement of T c to 2.2 K is observed in Eu 0.5 La 0.5 BiS 2 F. Upon application of pressure T c is further enhanced upto ~10 K (P = 2.5 GPa). Eu 0.5 La 0.5 BiS 2 F is semiconducting down to 3 K. An onset of superconductivity like feature is seen at 2.2 K at ambient pressure. At a pressure above 1.38GPa, the T c onset remains invariant at 10 K but the T c (ρ=0) is increased to above 8.2 K. There is a possible crystallographic transformation by application of pressure from a structure of low T c to a structure corresponding to high T c .