Departures from Stoichiometry of BiTeI Crystals Grown from the Vapour Phase

Abstract

BiTeI crystals grown from the vapour phase are chemically analysed and their Hall coeficient and electrical conductivity are measured. The products of thermal dissociation of BiTeI crystals are studied by means of mass spectrometry. The excess iodine found and the free carrier concentration determined from the Hall coefficient are used for formulating a model of point defects in the BiTeI crystals. Excess oidine atoms enter sites in the tellurium sublattice, and bismuth vacancies with one negative charge are formed simultaneously. The crystal prepared from the vapour phase may be described by the formula Bi1−x/3Te1−xI1+x + ⅔xé.

Imaging ambipolar two-dimensional carriers induced by the spontaneous electric polarization of a polar semiconductor BiTeI

“…By counting defects in several topographic images, we estimate that the density of these defects is about 5−8×10 19 cm −3 . This value, slightly larger than the bulk electron density (2.5×10 19 cm −3 ), is just as expected because a considerable amount of acceptors exists in this material as well as predominant donors 43 . Therefore, the density of defects near the surface is virtually identical to that in the bulk without increased by cleavage.…”

Theory of Anomalous Optical Properties of Bulk Rashba Conductor

“…The interaction (13) is the interaction Hamiltonian proposed to describe cross correlation effects in insulator multiferroics, and the vector A and Q ij in this context are toroidal and quadrupole moments, respectively [32]. The form of interaction between the toroidal moment and the electromagnetic fields in equation (13) suggests that the edge singularity is a common feature of toroidal moment-induced directional dichroism. In fact, the energies of lights having positive and negative q • A get shifted according to the interaction; this energy difference results in directional dichroism if the interband transition matrix element depends on the energy.…”

“…Bi vacancies [13], was recently observed to have a large Rashba splitting of α = 3.85 eVÅ [14]; a large magneto-optical (Kerr) effect [15] and a giant spin-polarized photocurrent [16] were also discovered.…”

“…It has been observed that topological insulators, the extreme cases of Rashba systems where the quadratic term in the dispersion disappears, have intriguing features such as a coupled collective mode of spin and charge (spin plasmon) on the surface [12]. Bulk BiTeI, a semiconductor where carrier electrons are introduced by Bi vacancies [13], was recently observed to have a large Rashba splitting of α = 3.85 eVÅ [14]; a large magneto-optical (Kerr) effect [15] and a giant spin-polarized photocurrent [16] were also discovered.…”