Antiperovskite superconductor LaPd${}_3$P with noncentrosymmetric cubic structure

Abstract

Antiperovskites are a promising candidate structure for the exploration of new materials. We discovered an antiperovskite phosphide, LaPd${}_3$P, following our recent synthesis of $A$Pd${}_3$P ($A$ = Ca, Sr, Ba). While $A$Pd${}_3$P and (Ca,Sr)Pd${}_3$P were found to be tetragonal or orthorhombic systems, LaPd${}_3$P is a new prototype cubic system ($a$ = 9.0317(1) A) with a noncentrosymmetric space group ($I-43m$). LaPd${}_3$P exhibited superconductivity with a transition temperature ($T_{\mathrm{c}}$) of 0.28 K. The upper critical field, Debye temperature, and Sommerfeld constant ($\gamma$) were determined as 0.305(8) kOe, 267(1) K, 6.06(4) mJ mol-1 K-2 f.u.-1, respectively. We performed first-principles electronic band structure calculations for LaPd${}_3$P and compared the theoretical and experimental results. The calculated Sommerfeld constant (2.24 mJ mol-1 K-2 f.u.-1) was much smaller than the experimental value of $\gamma$ because the Fermi energy ($E_{\mathrm{F}}$) was located slightly below the density of states (DOS) pseudogap. This difference was explained by the increase in the DOS at $E_{\mathrm{F}}$ due to the approximately 5 at.% La deficiency (hole doping) in the sample. The observed Tc value was much lower than that estimated using the Bardeen-Cooper-Schrieffer equation. To explain the discrepancy, we examined the possibility of an unconventional superconductivity in LaPd${}_3$P arising from the lack of space inversion symmetry.

13 pages, 5 figures, 4 tables

References in corpus (3)

• New anti-perovskite-type Superconductor ZnNyNi3
• Superconductivity induced by Mg deficiency in non-centrosymmetric phosphide Mg${}_2$Rh${}_3$P
• Superconductivity of centrosymmetric and non-centrosymmetric phases in antiperovskite (Ca,Sr)Pd${}_3$P

Cited by in corpus (1)

• Hidden Structural and Superconducting Phase Induced in Antiperovskite Arsenide SrPd${}_3$As