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

We study the effect of hydrostatic pressure on the electrical transport, magnetic, and structural properties of MnBi2Te4 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, MnBi2Te4 shows a metallic conducting behavior with a cusplike anomaly at around T-N approximate to 24 K, where it undergoes a long-range antiferromagnetic (AF) transition. With increasing pressure, T-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-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-c1 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 Mn-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.