Magnetic properties of Mn-doped Bi$_2$Se$_3$ compound: temperature dependence and pressure effects

TL;DR

This study investigates the magnetic susceptibility of Mn-doped Bi$_2$Se$_3$ across various temperatures and pressures, revealing antiferromagnetic interactions and how pressure influences magnetic properties, providing insights into Mn moment interactions.

Contribution

It presents the first detailed analysis of pressure effects on magnetic susceptibility in Mn-doped Bi$_2$Se$_3$, highlighting the pressure dependence of the Curie-Weiss temperature.

Findings

Magnetic susceptibility follows Curie-Weiss law with S=5/2 for all samples.

Effective Mn magnetic moments are consistent with high-spin Mn ions.

Pressure decreases the Curie-Weiss temperature, indicating altered magnetic interactions.

Abstract

Magnetic susceptibility $\chi$ of Bi$_{2-x}$Mn$_{x}$Se$_3$ ($x = 0.01-0.2$) was measured in the temperature range $4.2-300$ K. For all the samples, a Curie-Weiss behaviour of $\chi(T)$ was revealed with effective magnetic moments of Mn ions corresponding to the spin value S=5/2, which couple antiferromagnetically with the paramagnetic Curie temperature $\Theta\sim -50$ K. In addition, for the samples of nominal composition $x$ = 0.1 and 0.2 the effect of a hydrostatic pressure $P$ up to 2 kbar on $\chi$ has been measured at fixed temperatures 78 and 300 K that allowed to estimate the pressure derivative of $\Theta$ to be d$\Theta$/d$P\sim-0.8$ K/kbar. Based on the observed behaviour of $\Theta$ with varied Mn concentration and pressure, a possible mechanism of interaction between localized Mn moments is discussed.