Magnetization driven metal - insulator transition in strongly disordered Ge:Mn magnetic semiconductors

TL;DR

This paper investigates how magnetic disorder causes a metal-insulator transition in disordered Ge:Mn semiconductors, revealing universal scaling laws and extreme magnetoresistance effects linked to magnetic ordering.

Contribution

It demonstrates the role of magnetic disorder in inducing localization and the metal-insulator transition, with new universal scaling behavior observed in Ge:Mn alloys.

Findings

Magnetoresistance reaches thousands of percent.

Universal scaling law for magnetoresistance is observed.

Magnetic disorder leads to charge carrier localization.

Abstract

We report on the temperature and field driven metal-insulator transition in disordered Ge:Mn magnetic semiconductors accompanied by magnetic ordering, magnetoresistance reaching thousands of percents and suppression of the extraordinary Hall effect by a magnetic field. Magnetoresistance isotherms are shown to obey a universal scaling law with a single scaling parameter depending on temperature and fabrication. We argue that the strong magnetic disorder leads to localization of charge carriers and is the origin of the unusual properties of Ge:Mn alloys.