Magnetic, electronic and transport properties of high-pressure-synthesized chiralmagnets Mn$_{1-x}$Rh$_x$Ge (B20)

TL;DR

This study investigates how pressure, composition, and magnetic ordering influence the structural, magnetic, and electronic properties of Mn$_{1-x}$Rh$_x$Ge compounds, revealing composition-dependent magnetic behavior and a transition from semiconducting to metallic states.

Contribution

It provides new insights into the pressure and composition dependence of magnetic and electronic properties of Mn$_{1-x}$Rh$_x$Ge, supported by experimental and ab initio calculations.

Findings

Magnetic moments decrease linearly with Rh concentration.

Magnetic ordering temperature varies with pressure depending on Rh content.

Intermediate compositions show a transition from semiconducting to metallic in the magnetically ordered state.

Abstract

We report on structural, magnetic and transport properties of a new set of the high-pressuresynthesized compounds Mn$_{1-x}$Rh$x$Ge ($0 \leq x \leq 1$) with the chiral magnetic ordering. The magnetic and transport properties depend substantially on the concentration of rhodium (x) and the pressure. The saturation magnetic moment corresponds to a known high-spin value for pristine MnGe (x = 0) and decreases almost linearly with increasing concentration $x$. In addition, XMCD spectra taken at 10 K and 2 T indicate magnetic polarization of the Rh 4d electron states and Ge $4p$ states, which decreases with $x$, too. In rhodium rich compounds ($x \geq 0.5$) the temperature of the magnetic ordering increases significantly with pressure, whereas in manganese rich compounds ($x < 0.5$) the temperature decreases. Three different tendencies are also found for several structural and transport properties. In the intermediate range ($0.3 \leq x \leq 0.7$) samples are semiconducting in the paramagnetic phase, but become metallic in the magnetically ordered state. We carried out ab initio density-functional calculations of Mn$_{1-x}$Rh$_x$Ge at various concentrations $x$ and traced the evolution of electronic and magnetic properties. The calculation results are in good agreement with the measured magnetic moments and qualitatively explain the observed trends in transport properties.