Bulk single crystal growth and magneto-transport properties of α-MnTe

Abstract

The collinear antiferromagnetic α-MnTe has recently attracted widespread attention as an altermagnet. Here, we reported the hexagonal and centimeter sized single crystals of α-MnTe are grown using the Sb-flux technique and a thorough characterization of their composition, structural, magnetic, and electric properties. The growth conditions were optimized by investigating the phase diagram of α-MnTe. The quality and compositional homogeneity of the crystals were examined through x-ray Laue diffraction and energy dispersive spectrometer. Room temperature x-ray powder diffraction and a structure refinement confirmed a single phase NiAs-type hexagonal structure with P6₃/mmc space group. Magnetization measurements on a single crystal reveal the transition temperature of the antiferromagnetic correlations is around 310 K. We experimentally revealed that when magnetic field perpendicular to the in-plane direction can induce weak ferromagnetic behavior. Additionally, we investigated the electrical properties of α-MnTe under ambient and high pressures. At ambient pressure, the upturn in the resistance curve at low temperature can be attributed to electron weak localization behavior caused by quantum interference effects. Under high pressure, α-MnTe undergoes a structural phase transition to γ-MnTe. The first-principles calculation indicates that the weakening of p–d hybridization under pressure enhances the activity of localized d-electrons near the Fermi level in the conduction band. As pressure increases, the metallicity of MnTe is strengthened. Our research findings lay the foundation for further studies on α-MnTe as a promising candidate for altermagnetic applications.