Ferromagnetism in Cr-doped topological insulator TlSbTe2

TL;DR

This study reports the synthesis of Cr-doped TlSbTe2 as a new ferromagnetic topological insulator, with low Curie temperatures and observable quantum oscillations, expanding understanding of magnetic doping in topological materials.

Contribution

It demonstrates successful Cr doping in TlSbTe2 to induce ferromagnetism and explores the limits of Cr solubility and magnetic properties in this material.

Findings

Cr can be incorporated up to 1% in TlSbTe2.

Maximum Curie temperature observed is about 4 K.

SdH oscillations indicate quantum coherence in doped samples.

Abstract

We have synthesized a new ferromagnetic topological insulator by doping Cr to the ternary topological-insulator material TlSbTe2. Single crystals of Tl_{1-x}Cr_{x}SbTe2 were grown by a melting method and it was found that Cr can be incorporated into the TlSbTe2 matrix only within the solubility limit of about 1%. The Curie temperature \theta_c was found to increase with the Cr content but remained relatively low, with the maximum value of about 4 K. The easy axis was identified to be the c-axis and the saturation moment was 2.8 \mu_B (Bohr magneton) at 1.8 K. The in-plane resistivity of all the samples studied showed metallic behavior with p-type carriers. Shubnikov-de Hass (SdH) oscillations were observed in samples with the Cr-doping level of up to 0.76%. We also tried to induce ferromagnetism in TlBiTe2 by doping Cr, but no ferromagnetism was observed in Cr-doped TlBiTe2 crystals within the solubility limit of Cr which turned out to be also about 1%.