Pressure variation of Rashba spin splitting toward topological transition in the polar semiconductor BiTeI

Abstract

BiTeI is a polar semiconductor with gigantic Rashba spin-split bands in bulk. We have investigated the effect of pressure on the electronic structure of this material via magnetotransport. Periods of Shubunikov-de Haas (SdH) oscillations originating from the spin-split outer Fermi surface and inner Fermi surface show disparate responses to pressure, while the carrier number derived from the Hall effect is unchanged with pressure. The associated parameters which characterize the spin-split band structure are strongly dependent on pressure, reflecting the pressure-induced band deformation. We find the SdH oscillations and transport response are consistent with the theoretically proposed pressure-induced band deformation leading to a topological phase transition. Our analysis suggests the critical pressure for the quantum phase transition near P c = 3.5 GPa. The spin-orbit interaction (SOI) plays a central role in determining the behavior of electrons in solids. In addition to the SOI-related subjects of spintronics, such as generation, manipulation, and detection of spin information, there has recently been an intense focus on the effect of the SOI on the electronic band structure itself. In particular, an extremely large SOI in small gap semiconductors has been shown theoretically [1][2][3][4] and experimentally [5][6][7] to give rise to a new exotic state of matter known as the topological insulator (TI). As probed by numerous experiments including angle resolved photoemission spectroscopy (ARPES) [6,7] and magnetotransport [8][9][10][11][12], this bulk insulating phase hosts metallic surface states composed of spin-polarized Dirac fermions, attracting both fundamental and technological interest [13,14].The spin texture in the momentum space of the TI surface state is analogous to a Rashba-type spin structure [15]. A Rashba-type structure can be expected in a system with broken inversion symmetry so that electrons are subject to an effective SOI driven k-dependent Zeeman field perpendicular to both the polar axis and crystal momentum [15]. This effect in TIs and other Rashba-type materials lifts spin degeneracy in the Fermi surface, resulting in a chiral spin texture. Historically, this effect has been studied in surface [16][17][18] and interface [19] systems and more recently for the surface of TIs [20], where such a breaking of inversion symmetry naturally arises. More recently, a bulk (three-dimensional) polar semiconductor BiTeI has been shown to host a large Rashba-type spin-split bulk band structure [21]. Similar to the case of TIs, ARPES [21][22][23][24] and magnetotransport [25][26][27] have identified several salient features that point to the unique role of SOI in the electronic properties of these materials. It is widely expected that more exotic phases may exist also at the nexus of such bulk polar materials.It was recently predicted by first-principles calculations that BiTeI shows a topological transition under pressure [28]. Figure 1 shows the evolution of the band structure of BiTeI with the app...

Structural, vibrational, and electrical study of compressed BiTeBr

“…A similar pressure dependence of the k dispersion of the bands forming the quasidirect band gap has been found in our band structure calculations for BiTeI [47]. This change of the band dispersion is consistent with recent estimations obtained from Shubnikov-de Haas oscillations in BiTeI under pressure, where samples with a high electron concentration have been found to cross the inner Dirac cone of the conduction band at the A point at high pressures [56].…”

“…Above this pressure, a quicker increase in resistivity is found, which can be attributed to the creation of defects, precursors of the phase transition above 6-7 GPa as observed in XRD and RS measurements. The pressure increase of the resistivity in BiTeBr at low pressure contrasts with the decrease reported for the resistivity of relatively highly doped BiTeI samples at room temperature up to 3 GPa [55,56]. Before explaining the behavior of resistivity with increasing pressure in BiTeBr we will analyze first the pressure dependence of the Seebeck coefficient and of the electron concentration and mobility in our samples.…”

Pressure effects on crystal and electronic structure of bismuth tellurohalides

“…Recently it was predicted that BiTeI transforms from a trivial phase into a TI by applying an external pressure of 1.7-4.1 GPa [20,21]. The topological phase transition (TPT) was also observed experimentally at 2-2.9GPa and 3.5GPa using infrared spectroscopy [22] and Shubnikov-de Haas oscillations measurements, [23] respectively. In [27], within optical measurements the TPT does not observed.…”

Thermoelectric probe for Fermi surface topology in the three-dimensional Rashba semiconductor BiTeI

“…The Rashba-type band structure is unique in the sense that a small inner Fermi surface (IFS) with a spin-polarized Dirac fermion is buried in the large outer Fermi surface (OFS) also with the chiral spin texture. Transport properties originating from the Rashba-type band structure have been reported in the previous studies, such as the characteristic Shubnikov-de Haas (SdH) oscillations [7][8][9][10][11][12] and magnetophotocurrent measurement [13].A recent systematic study of SdH oscillations in BiTeI [11] could capture the signature of the Fermi surface topology change. With increasing the mobility and varying the carrier density by Cu doping (see also Ref.…”