Low-Dilution Limit of Zn_{1-x}Mn_{x}GeAs_{2}: electrical and magnetic properties

TL;DR

This study investigates the electrical and magnetic properties of Zn_{1-x}Mn_{x}GeAs_{2} crystals with low Mn content, revealing defect-driven conductivity, weak localization effects, and weak magnetic interactions, with implications for dilute magnetic semiconductors.

Contribution

It provides new insights into the electrical transport and magnetic interactions in low-Mn-content ZnMnGeAs2, including the estimation of the Mn-hole exchange integral using the RKKY model.

Findings

Negative magnetoresistance up to -50% linked to weak localization.

Random Mn-distribution occurs only at the lowest Mn content.

Presence of weak ferromagnetic or antiferromagnetic interactions with small Curie-Weiss temperatures.

Abstract

We present the studies of electrical transport and magnetic interactions in Zn_{1-x}Mn_{x}GeAs_{2} crystals with low Mn content 0 \leq x \leq 0.043. We show that the ionic-acceptor defects are mainly responsible for the strong p-type conductivity of our samples. We found that the negative magnetoresistance (MR) with maximum values of about -50% is related to the weak localization phenomena. The magnetic properties of Zn1-xMnxGeAs2 samples show that the random Mn-distribution in the cation sites of the host lattice occurs only for the sample with the lowest Mn-content, x=0.003. The samples with higher Mn-content show a high level of magnetic frustration. Nonzero Curie-Weiss temperature observed in all our samples indicates that weak ferromagnetic (for x=0.003) or antiferromagnetic (for x>0.005) interactions with |{\Theta}|<3 K are present in this system. The RKKY model, used to estimate the Mn-hole exchange integral Jpd for the diluted Zn/0.997/Mn/0.003/GeAs/2/ sample, makes possible to estimate the value of Jpd =(0.75+/-0.09) eV.