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 Néel 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 Néel 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.
| Original language | English |
|---|---|
| Article number | 045121 |
| Journal | Physical Review B |
| Volume | 106 |
| Issue number | 4 |
| DOIs | |
| State | Published - Jul 15 2022 |
Funding
We thank Robert J. McQueeney and Steven Winter for useful discussions. Work at UCLA was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0021117. T.-R.C. was supported by the Young Scholar Fellowship Program from the Ministry of Science and Technology (MOST) in Taiwan, under a MOST grant for the Columbus Program No. MOST111-2636-M-006-014, NCKU, Taiwan, and National Center for Theoretical Sciences, Taiwan. Work at NCKU was supported by the MOST, Taiwan, under Grant No. MOST107-2627-E-006-001 and Higher Education Sprout Project, Ministry of Education to the Headquarters of University Advancement at NCKU. Work at ORNL was supported by U.S. DOE BES Early Career Award No. KC0402010 under Contract No. DE-AC05-00OR22725 and used resources at the Spallation Neutron Source and the High Flux Isotope Reactor, DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory. I.M. acknowledges support from DOE under the Grant No. DE-SC0021089. C.H. was supported by the Julian Schwinger Fellowship at UCLA.