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MnBi2Te4 has attracted tremendous research interest recently as the first intrinsic antiferromagnetic (AF) topological insulator. It undergoes a long-range AF order at TN = 24 K accompanied with a cusp-like anomaly in the metallic resistivity. Here, we studied the effect of hydrostatic pressure on its electrical transport properties up to 12.5 GPa by using a cubic anvil cell apparatus. We find that TN determined from the resistivity anomaly first increases slightly with pressure and then decreases until vanished completely at ~7 GPa. Intriguingly, its resistivity rho(T) is enhanced gradually by pressure, and evolves from metallic to activated behavior as the AF order is suppressed. From the Hall resistivity measurements, we confirm that the n-type carriers dominate the transport properties and the carrier density is raised by pressure. In addition, the critical magnetic field Hc1 ~3.3 T at 0 GPa for the spin-flop transition to the canted AF state is found to increase to ~ 5 T and 7.5 T at 1 and 3 GPa. High-pressure XRD evidenced no structural transition up to 12.8 GPa. Based on the Hall resistivity results and first-principles calculations, we proposed that the intralayer direct AF interactions are strengthened by pressure and the competition between AF and FM interactions not only prevents long-range magnetic order but also promotes charge carrier localizations through enhance magnetic fluctuations at high pressures.
We have successfully grown cm3-size single crystals of the metallic-ferromagnet Sm2Mo2O7 by the floating-zone method using an infrared-red image furnace. The growth difficulties and the remedies found using a 2-mirror image furnace are discussed. Mag
The layered honeycomb magnet alpha-RuCl3 has been proposed as a candidate to realize a Kitaev spin model with strongly frustrated, bond-dependent, anisotropic interactions between spin-orbit entangled jeff=1/2 Ru4+ magnetic moments. Here we report a
One of the most strikingly universal features of the high temperature superconductors is that the superconducting phase emerges in the close proximity of the antiferromagnetic phase, and the interplay between these two phases poses a long standing ch
I study the structural and magnetic instabilities in LaNiO$_3$ using density functional theory calculations. From the non-spin-polarized structural relaxations, I find that several structures with different Glazer tilts lie close in energy. The $Pnma
We calculate Raman response functions on the Fermi surface in metallic cuprates.