Suppression of the antiferromagnetic metallic state in the pressurized MnBi2Te4 single crystal

Abstract

We study the effect of hydrostatic pressure on the electrical transport, magnetic, and structural properties of $\mathrm{MnB}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{4}$ by measuring its resistivity, Hall effect, and x-ray diffraction under pressures up to 12.8 GPa supplemented by the first-principles calculations. At ambient pressure, $\mathrm{MnB}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{4}$ shows a metallic conducting behavior with a cusplike anomaly at around ${T}_{\mathrm{N}}\ensuremath{\approx}24\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, where it undergoes a long-range antiferromagnetic (AF) transition. With increasing pressure, ${T}_{\mathrm{N}}$ determined from the resistivity anomaly first increases slightly with a maximum at around 2 GPa and then decreases until vanishing completely at about 7 GPa. Intriguingly, its resistivity is enhanced gradually by pressure and even evolves from metallic to semimetal or semiconductinglike behavior as ${T}_{\mathrm{N}}$ is suppressed. However, the density of the $n$-type charge carrier that remains dominant under pressure increases with pressure. In addition, the interlayer AF coupling seems to be strengthened under compression, since the critical field ${H}_{\mathrm{c}1}$ for the spin-flop transition to the canted AF state is found to increase with pressure. No structural transition was evidenced up to 12.8 GPa, but some lattice softening was observed at about 2 GPa, signaling the occurrence of an electronic transition or crossover from a localized to itinerant state. We have rationalized these experimental findings by considering the pressure-induced enhancement of antiferromagnetic/ferromagnetic competition and partial delocalization of $\mathrm{Mn}\text{\ensuremath{-}}3d$ electrons, which not only destroys long-range AF order but also promotes charge-carrier localization through enhanced spin fluctuations and/or the formation of a hybridization gap at high pressure.