Temperature Studies of Raman Spectra in MnBi 2 Te 4 and MnSb 2 Te 4 Magnetic Topological Insulators

Raman spectra of magnetic topological crystalline insulators in a wide temperature range including the magnetic ordering region are studied in detail. The anharmonicity parameters and Grüneisen mode parameters of Raman-active phonons in the studied crystals have been determined. It has been shown that the temperature dependence of the frequency of the A_1g^(1) ( 48 cm –1 ) phonon in MnBi 2 Te 4 coincides within ±0.1 cm –1 with the standard anharmonic model disregarding the spin–phonon coupling. The polarization dependences of Raman spectra in the MnSb 2 Te 4 crystals indicate that Sb and Mn atoms are strongly mixed in them unlike the isostructural MnBi 2 Te 4 crystals.