Abstract
An intrinsic antiferromagnetic topological insulator MnBi2Te4 arises when intercalating a Mn-Te bilayer chain in a topological insulator, Bi2Te3. We present observations on the inter- and intralayer phonon modes of the generalized MnBi2nTe3n+1(n=1,2,3,4) family using cryogenic low-frequency Raman spectroscopy with various polarization configurations. Two peaks at 66 and 112cm-1 show abnormal perturbation in Raman linewidths below magnetic transition temperature due to spin-phonon coupling. In MnBi4Te7, Bi2Te3 layers induce Davydov splitting of the A1g mode around 137cm-1 at 5 K. The out-of-plane interlayer force constant estimated using the linear chain model was (3.98±0.14)×1019N/m3, three times weaker than that of Bi2Te3. Adding more Bi2Te3 layers, such as MnBi6Te10 and MnBi8Te13, makes Bi2Te3 properties more dominant than magnetic properties. Our work experimentally and theoretically discovers the dynamics of phonon modes of MnBi2nTe3n+1 family, facilitating utilization of magnetic topological heterostructures.
| Original language | English |
|---|---|
| Article number | 013108 |
| Journal | Physical Review Research |
| Volume | 4 |
| Issue number | 1 |
| DOIs | |
| State | Published - Mar 1 2022 |
Funding
We thank I. J. Park and Professor R. K. Lake at University of California, Riverside for helpful discussion on the phonon calculation. Y.C., J.H.K. and C.W.W acknowledge the support of UC Office of President (LFR-17-477237) and NSF (1810548 and 1611598). C.H. and N.N. acknowledge the support of single crystal growth and characterization by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0021117. A portion of this research used resources at the Center for Nanophase Materials Sciences, which is a U.S. DOE Office of Science User Facility. L.L. and X.K. acknowledge computational resources of the Computer and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. DOE under Contract No. DE-AC05-00OR22725. A.A.B. acknowledges the support of the U.S. DOE under Contract No. DE-SC0021020.