Anharmonicity of Lattice Vibrations in Bi 2 Se 3 Single Crystals

The temperature dependences of the Raman-active frequencies E_g^2 , A_1g^2 in layered Bi 2 Se 3 single crystals are studied. The contribution of the thermal expansion to a temperature variation in the frequencies is determined. The decay of the anisotropy of the elastic properties in layered Bi 2 Se 3 single crystals due to strong spin–orbit coupling is shown. The Gruneisen-mode parameters for phonons E_g^2 and A_1g^2 are calculated. Systematic features in the dependences of vibrational frequencies on the atomic masses in layered Bi 2 Te 3 , Bi 2 Se 3 , and Sb 2 Te 3 single crystals are determined.