Disorder-Promoted Splitting in Quasiparticle Interference at Nesting Vectors

Abstract

Inelastic interactions of quantum systems with environment usually wash coherent effects out. In the case of Friedel oscillations the presence of disorder leads to a fast decay of the oscillation amplitude. Here we show both experimentally and theoretically that in the three-dimensional topological insulator Bi 2 Te 3 there is a nesting-induced splitting of coherent scattering vectors which follows a peculiar evolution in energy. The effect becomes experimentally observable when the lifetime of quasiparticles shortens, due to disorder. The amplitude of the splitting allows evaluating the lifetime of the electrons. A similar phenomenon should be observed in any system with a well-defined scattering vector regardless of its topological properties.Predicted a long ago, recently discovered three-dimensional topological insulators (TIs) [1][2][3][4][5][6][7] are characterized by conducting surface states with the linear dispersion, Dirac cones, evolving in the bulk gap. In real materials, the Dirac cones are often regular only close to their origin, the Dirac point (DP). Both theories and experiments showed that far from the Dirac point, the circular shape of the constant energy contour evolves into a hexagon and then to a snowflake with sharp tips extending along six crystallographic directions. [8][9][10] The warping is present in Bi 2 Se 3 , 11-13 Pb(Bi,Sb) 2 Te 4 14 and other TI materials. 10,15

Magnetic Gap of Fe-Doped BiSbTe2Se Bulk Single Crystals Detected by Tunneling Spectroscopy and Gate-Controlled Transports

“…A local STM study of the flat terraces revealed well-ordered hexagonal lattices with randomly arranged atomic defects, reflecting its homogeneous substitution of (Bi, Sb, Fe) and (Te, Se) sites (see Figure a, the inset). We confirmed that the spatial electron density distribution near defects (not shown here) showed a typical spectrum for other Bi based tetradymites. − The form of fingerprints depends on the type of defects and their depth in the QLs; e.g., the surface has bright triangular dots corresponding to the chalcogen vacancies described in ref .…”

Superconducting Long-Range Proximity Effect through the Atomically Flat Interface of a Bi2Te3 Topological Insulator

“…Figure provides a summary of the structural properties of studied samples. The topographic STM image in Figure a obtained after in-vacuum Bi 2 Te 3 cleavage reveals the atomically clean surface on which typical structural defects − are observed. A typical d I ( V )/d V spectrum measured at the Bi 2 Te 3 surface in a large energy window around the Fermi level is presented in Figure b; the position of the Dirac point (DP), the top of the valence band (BVB), and the bottom of the conduction band (BCB) are indicated.…”

“…The topographic STM image in Fig. 1(a) obtained after in-vacuum Bi 2 Te 3 cleavage reveals the atomically clean surface on which typical structural defects [52][53][54] are observed. A typical dI(V )/dV spectrum measured at the Bi 2 Te 3 surface in a large energy window around the Fermi level is presented in Fig.…”

Resonant Oscillations of Josephson Current in Nb‐Bi2Te2.3Se0.7‐Nb Junctions

“…[23] As a result of the Ar-etching, the nano-crystals under the Nbelectrodes get damaged and are characterized by the short electron mean free path. [26] Only a few ballistic channels remain wellconnected via these damaged regions. Moreover, a band bending is likely to occur in the part of the crystal covered with the Nb electrodes.…”