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arXiv · 1412.7362

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

B. Wiendlocha·M. J. Winiarski·M. Muras·C. Zvoriste-Walters·J. -C. Griveau·S. Heathman·M. Gazda·T. Klimczuk
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Abstract

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 450^oC. 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)x10^{-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 {λ_{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 {λ_{ep}} and its evolution with pressure. Theoretical results explain the experimentally observed decrease in Tc due to considerable lattice stiffening.

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B. Wiendlocha, M. J. Winiarski, M. Muras, C. Zvoriste-Walters, J. -C. Griveau, S. Heathman, M. Gazda, T. Klimczuk. 2015-01-19. Pressure effects on the superconductivity of HfPd2Al Heusler compound: Experimental and theoretical study. https://doi.org/10.1103/physrevb.91.024509

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