Magnetoresistance control in granular Zn/1-x-y/Cd/x/Mn/y/GeAs/2/ nanocomposite ferromagnetic semiconductors

TL;DR

This study investigates how the chemical composition of Zn/Cd/Mn/GeAs nanocomposites influences their magnetic and electrical properties, especially magnetoresistance, with potential applications in spintronics.

Contribution

It demonstrates control over magnetoresistance sign and magnitude in ferromagnetic semiconductors through compositional tuning of nanocomposite materials.

Findings

MnAs clusters induce room temperature ferromagnetism around 305 K.

Magnetoresistance sign can be switched from negative to positive by changing Cd content.

Negative magnetoresistance reaches -32% at 1.4 K, 13 T for x=0.85.

Abstract

We present studies of structural, magnetic and electrical properties of Zn/1-x-y/Cd/x/Mn/y/GeAs/2/ nanocomposite ferromagnetic semiconductor samples with changeable chemical composition. The presence of MnAs clusters induces in the studied alloy room temperature ferromagnetism with the Curie temperature, TC, around 305 K. The chemical composition of the chalcopyrite matrix controls the geometrical parameters of the clusters inducing different magnetoresistance effects in the crystals. The presence of ferromagnetic clusters in the alloy induces either negative or positive magnetoresistance with different values. The Cd-content allows a change of magnetoresistance sign in our samples from negative (for x = 0.85) to positive (for x = 0.12). The negative magnetoresistance present in the samples with x = 0.85 is observed at temperatures T < 25 K with maximum values of about -32% at T = 1.4 K and B = 13 T, strongly depending on the Mn content, y. The positive magnetoresistance present in the samples with x = 0.12 is observed with maximum values not exceeding 50% at B =13 T and T = 4.3 K, changing with the Mn content, y.