Pressure effects on the superconductivity of the HfPd2Al Heusler compound - Experimental and theoretical study

Polycrystalline HfPd2Al has been synthesized using the arc-melting method and studied under ambient pressure conditions by x-ray diffraction from room temperature up to 450oC. High pressure x-ray diffraction up to 23 GPa was also performed using Diacell-type membrane diamond anvil cells. The estimated linear thermal expansion coefficient was found to be α = 1.40(3)·10-5 K-1, and the bulk modulus derived from the fit to the 3rd order Birch-Murnaghan EOS (BMEOS) is B0 = 97(2) GPa. Resistivity studies under applied pressure (p ≤ 7.49 GPa) showed a linear decrease of superconducting critical temperature with increasing pressure and the slope dTc/dp = -0.13(1) K GPa-1. The same behavior is observed for the electron-phonon coupling constant ep(p) that changes from 0.67 to 0.6, estimated for p = 0.05 GPa and 7.49 GPa, respectively. First principles electronic structure and phonon calculation results are presented and used to estimate the magnitude of electron-phonon interaction ep and its evolution with pressure. Theoretical results explain the experimentally observed decrease in Tc due to considerable lattice stiffening.

WIENDLOCHA B.;  WINIARSKI M. J.;  MURAS M.;  ZVORISTE Carmen Elena;  GRIVEAU Jean-Christophe;  HEATHMAN Stephen;  GAZDA M.;  KLIMCZUK Tomasz; 

2015-01-20

AMER PHYSICAL SOC

JRC92346

1098-0121,   

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.91.024509,    https://journals.aps.org/prb/accepted/aa07aO24Kcc10724a3c028d09af1f50034ebfe6cd,    http://arxiv.org/abs/1412.7362,    https://publications.jrc.ec.europa.eu/repository/handle/JRC92346,   

10.1103/PhysRevB.91.024509,