From E_{2g} to other modes : Effects of pressure on electron-phonon interaction in MgB_2

We study the effects of pressure on the electron-phonon interaction in MgB_2 using density-functional-based methods. Our results show that the superconductivity in MgB_2 vanishes by 100 GPa, and then reappears at higher pressures. In particular, we find a superconducting transition temperature T_c \~ 2 K for mu*=0.1 at a pressure of 137 GPa.Comment: 4 pages, 6 figures; one figure and discussion on phonon softening adde

Comment on "Doping Driven (π,0\pi,0) Nesting and Magnetic Properties of Fe1+x_{1+x}Te Superconductors" [Phys. Rev. Lett. 103, 067001 (2009)]

In this Comment, using Korringa-Kohn-Rostoker coherent-potential approximation method in the atomic-sphere approximation (KKR-ASA CPA) to describe the effects of disorder due to excess Fe in FeTe alloys, we show that (i) the rigid-band approximation is inadequate to describe the effects of disorder and its application leads to an incorrect description of the underlying physics, (ii) the rigid-band energy shift of ~0.76 eV for going from FeTe to Fe_{1.068}Te (or Fe_{1.063}Te), as obtained by Han and Savrasov (Phys. Rev. Lett. 103, 067001(2009)), is inconsistent with our FP-LMTO as well as the KKR-ASA results, and thus the FS of Fe_{1.063}Te shown in Fig. 3(b) of their paper is not correct.Comment: 1 page, 1 fi

Magnetism in Transition metal doped Cubic SiC

We report here our study on SiC doped with transition metals using first principle density functional theory calculations. We have considered cubic SiC with 3d transition metals as substitutional impurities for Si and C site separately. Cubic SiC doped with Cr, Mn, show ferromagnetism whereas with Sc, Ti, V and Co show site dependency of magnetic properties. Rests of the impurities are found to be non-magnetic.Comment: Presented in the 55th DAE-Solid State Physics Symposium, 26th to 30th December, 2010, Manipal University, Manipal, India; AIP Conf. Proc. 1349, 1087-1088 (2011