Surface phonons in the 1/f noise of Bi2Se3.

Temperature dependence of the 1/f noise intensity in Bi₂Se₃ features a weak structure of unknown origin. Comparing the noise structure with the Raman spectrum of Bi₂Se₃, we found that it is the image of the surface phonon spectrum of this topological insulator. It also revealed that the low intensity of both noise bands composing the structure in the topological regime is due to the weak interaction of the Dirac electrons with the surface phonons of Bi₂Se₃. One of these noise bands has been found to correspond to the boson peak of the amorphous Se surface atoms, while the other one is well fitted by the Eliashberg function of amorphous Bi. It indicates that the interaction of the Dirac electrons with the thermal motion of the Se and Bi atoms, in the first and second atomic layers of the first quintuple Se–Bi–Se–Bi–Se surface cell, respectively, is the microscopic source of the surface 1/f noise in this quantum material. A step-like noise increase observed at a surface-bulk transition in a Bi₂Se₃ film is assigned to a Fano resonance. This proves that the electron–phonon coupling is involved in the microscopic mechanism of 1/f noise in solids. [ABSTRACT FROM AUTHOR]