Abstract
As the first intrinsic antiferromagnetic topological insulator, MnBi2Te4 has provided a material platform to realize various emergent phenomena arising from the interplay of magnetism and band topology. Here, by investigating (Mn1−xPbx)Bi2Te4(0≤x≤0.82) single crystals via the x-ray, electrical transport, magnetometry and neutron measurements, chemical analysis, external pressure, and first-principles calculations, we reveal the magnetic dilution effect on the magnetism and band topology in MnBi2Te4. With increasing x, both lattice parameters a and c expand linearly by around 2%. All samples undergo the paramagnetic to A-type antiferromagnetic transition with the Nˊeel temperature decreasing lineally from 24 K at x=0 to 2 K at x=0.82. Our neutron data refinement of the x=0.37 sample indicates that the ordered moment is 4.3(1)μB/Mn at 4.85 K and the amount of the MnBi antisites is negligible within the error bars. Isothermal magnetization data reveal a slight decrease of the interlayer plane-plane antiferromagnetic exchange interaction and a monotonic decrease of the magnetic anisotropy due to diluting magnetic ions and enlarging the unit cell. For x=0.37, the application of external pressures enhances the interlayer antiferromagnetic coupling, boosting the Nˊeel temperature at a rate of 1.4 K/GPa and the saturation field at a rate of 1.8 T/GPa. Furthermore, our first-principles calculations reveal that the band inversion in the two end materials, MnBi2Te4 and PbBi2Te4, occurs at the Γ and Z point, respectively, while two gapless points appear at x= 0.44 and x= 0.66, suggesting possible topological phase transitions with doping.
