Pressure effects on the superconductivity of theHfPd2AlHeusler compound: Experimental and theoretical study
| Autor: | Michał J. Winiarski, C. Zvoriste-Walters, Tomasz Klimczuk, M. Muras, S. Heathman, Maria Gazda, Jean-Christophe Griveau, Bartlomiej Wiendlocha |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Physical Review B. 91 |
| ISSN: | 1550-235X 1098-0121 |
| Popis: | Polycrystalline ${\mathrm{Hf}\phantom{\rule{1.0pt}{0ex}}\mathrm{Pd}}_{2}\mathrm{Al}$ has been synthesized using the arc-melting method and studied under ambient-pressure conditions by x-ray diffraction from room temperature up to 450 \ifmmode^\circ\else\textdegree\fi{}C. 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 $\ensuremath{\alpha}=1.40(3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$, and the bulk modulus derived from the fit to the third-order Birch-Murnaghan equation of state is ${B}_{0}=97(2)$ GPa. Resistivity studies under applied pressure $(p\ensuremath{\le}7.49\phantom{\rule{0.16em}{0ex}}\mathrm{GPa})$ showed a linear decrease of superconducting critical temperature with increasing pressure and the slope $d{T}_{c}/dp=\ensuremath{-}0.13(1)\phantom{\rule{0.16em}{0ex}}\mathrm{K}\phantom{\rule{0.16em}{0ex}}{\mathrm{GPa}}^{\ensuremath{-}1}$. The same behavior is observed for the electron-phonon coupling constant ${\ensuremath{\lambda}}_{\mathrm{ep}}(p)$ that changes from 0.67 to 0.6, estimated for $p=0.05$ 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 ${\ensuremath{\lambda}}_{\mathrm{ep}}$ and its evolution with pressure. Theoretical results explain the experimentally observed decrease in ${T}_{c}$ due to considerable lattice stiffening. |
| Databáze: | OpenAIRE |
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