Superconductivity in ternary Mg$_4$Pd$_7$As$_6$

TL;DR

This paper reports the discovery and characterization of a new superconductor Mg$_4$Pd$_7$As$_6$ with a transition temperature of 5.45 K, highlighting its structure, properties, and conventional electron-phonon pairing mechanism.

Contribution

It introduces a new ternary superconductor Mg$_4$Pd$_7$As$_6$ with detailed structural, electronic, and phononic analysis, confirming conventional superconductivity.

Findings

Superconducting transition temperature $T_c=5.45$ K.

Confirmed structure as U$_4$Re$_7$Si$_6$ type.

Electron-phonon coupling parameter $oxed{ ext{λ} ext{~} 0.72-0.76}$, indicating moderate coupling.

Abstract

We report the synthesis and characterization of a new compound Mg$_4$Pd$_7$As$_6$, which was found to be a superconductor with $T_c=5.45$~K. Powder X-ray diffraction confirms the U$_4$Re$_7$Si$_6$ structure (space group $Im$-$3m$, no. 229) with the lattice parameter $a$ = 8.2572(1)~\AA. Magnetization, specific heat, and electrical resistivity measurements indicate that it is a moderate-coupling ($\lambda = 0.72$) type-II superconductor. The electronic and phonon structures are calculated, highlighting the importance of antibonding Pd-As interactions in determining the properties of this material. The calculated electron-phonon copling parameter $\lambda = 0.76$ agrees very well with the experimental finding, which confirms the conventional pairing mechanism in Mg$_4$Pd$_7$As$_6$.