Tuning of Electrical, Magnetic, and Topological Properties of Magnetic Weyl Semimetal Mn$_{3+x}$Ge by Fe doping

TL;DR

This study demonstrates how Fe doping in Mn$_{3+x}$Ge modulates its electrical, magnetic, and topological properties, revealing transitions from metallic to semiconducting and insulating states, and inducing new magnetic phenomena like spin-glass and topological Hall effects.

Contribution

It provides new insights into tuning the properties of magnetic Weyl semimetals through Fe doping, highlighting the emergence of topological Hall states and magnetic transitions.

Findings

Fe doping alters electrical behavior from metallic to semiconducting and insulating.

Fe doping enhances in-plane ferromagnetism and induces spin-glass states.

Topological Hall effect appears at specific Fe doping levels.

Abstract

We report on the tuning of electrical, magnetic, and topological properties of the magnetic Weyl semimetal (Mn$_{3+x}$Ge) by Fe doping at the Mn site, Mn$_{(3+x)-\delta}$Fe$_{\delta}$Ge ($\delta$=0, 0.30, and 0.62). Fe doping significantly changes the electrical and magnetic properties of Mn$_{3+x}$Ge. The resistivity of the parent compound displays metallic behavior, the system with $\delta$=0.30 of Fe doping exhibits semiconducting or bad-metallic behavior, and the system with $\delta$=0.62 of Fe doping demonstrates a metal-insulator transition at around 100 K. Further, we observe that the Fe doping increases in-plane ferromagnetism, magnetocrystalline anisotropy, and induces a spin-glass state at low temperatures. Surprisingly, topological Hall state has been noticed at a Fe doping of $\delta$=0.30 that is not found in the parent compound or with $\delta$=0.62 of Fe doping. In addition, spontaneous anomalous Hall effect observed in the parent system is significantly reduced with increasing Fe doping concentration.