Metal-insulator transition and superconductivity induced by Rh doping in binary Ru Pnictides RuPn (Pn = P, As and Sb)

TL;DR

This study explores how Rh doping suppresses metal-insulator and structural transitions in RuP and RuAs, leading to superconductivity near quantum critical points, revealing a new non-magnetic pathway to superconductivity.

Contribution

It demonstrates that Rh substitution in RuP and RuAs suppresses phase transitions and induces superconductivity near quantum critical points, offering novel insights into non-magnetic superconductivity mechanisms.

Findings

Superconductivity observed at Tc up to 3.7 K and 1.8 K.

Transitions suppressed at specific Rh concentrations (xc = 0.45 and 0.25).

Superconductivity occurs near the quantum critical point.

Abstract

Binary ruthenium pnictides, RuP and RuAs, with an orthorhombic MnP structure, were found to show a metal to a non-magnetic insulator transition at TMI = 270 K and 200 K, respectively. In the metallic region above TMI, a structural phase transition, accompanied by a weak anomaly in the resistivity and the magnetic susceptibility, indicative of a pseudo-gap formation, was identified at Ts = 330 K and 280 K, respectively. These two transitions were suppressed by substituting Ru with Rh. We found superconductivity with a maximum Tc = 3.7 K and Tc =1.8 K in a narrow composition range around the critical point for the pseudo-gap phase, Rh content xc = 0.45 and xc = 0.25 for Ru1-xRhxP and Ru1-xRhxAs, respectively, which may provide us with a novel non-magnetic route to superconductivity at a quantum critical point.