Direct observation of broken time-reversal symmetry on the surface of a magnetically doped topological insulator

Phys Rev Lett. 2011 May 20;106(20):206805. doi: 10.1103/PhysRevLett.106.206805. Epub 2011 May 17.

Abstract

We study interference patterns of a magnetically doped topological insulator Bi(2-x)Fe(x)Te(3+d) by using Fourier transform scanning tunneling spectroscopy and observe several new scattering channels. A comparison with angle-resolved photoemission spectroscopy allows us to unambiguously ascertain the momentum-space origin of distinct dispersing channels along high-symmetry directions and identify those originating from time-reversal symmetry breaking. Our analysis also reveals that the surface state survives far above the energy where angle-resolved photoemission spectroscopy finds the onset of continuum bulk bands.