Quantum oscillations and optical conductivity in Rashba spin-splitting BiTeI

Martin, C.; Mun, Eundeok; Berger, H.; Zapf, V. S.; Tanner, D. B.

doi:10.1103/physrevb.87.041104

Cited by 68 publications

(43 citation statements)

References 15 publications

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“…In contrast to the pressure-independent ρ yx , ρ xx is steadily reduced with increasing pressure. In addition, ρ xx shows clear SdH oscillations with two different periods with 1/B, as also reported in previous studies at ambient pressure [25][26][27]. Oscillations with a longer period in the low magnetic field region correspond to IFS, and those with a shorter period in the high-field region originate from OFS [ Fig.…”

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confidence: 59%

“…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.…”

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confidence: 95%

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

et al. 2014

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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...

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confidence: 95%

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

et al. 2014

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“…1(a)]. Compared with preceding studies [13][14][15], our BiTeI samples exhibit a relatively large resistivity ratio ρ 300 K /ρ 2 K = 4-5.8 [ Fig. 1(c)] and enhanced low temperature μ e typically between 800 and 3000 cm 2 /V s. The carrier density n e varies within the range of 1.2-6 × 10 19 /cm 3 for samples taken from the same ampoule, implying a composition gradient intrinsic to Bridgman growth [16].…”

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confidence: 99%

Transport signatures of Fermi surface topology change in BiTeI

Checkelsky

Kagawa

et al. 2015

Phys. Rev. B

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We report a quantum magnetotransport signature of a change in the Fermi surface topology in the Rashba semiconductor BiTeI with a systematic tuning of the Fermi level E F . Beyond the quantum limit, we observe a marked increase (decrease) in electrical resistivity when E F is above (below) the Dirac node that we show originates from the Fermi surface topology. This effect represents a measurement of the electron distribution on low-index (n = 0,−1) Landau levels and is uniquely enabled by the finite bulk k z dispersion along the c axis and strong Rashba spin-orbit coupling strength of the system. The Dirac node is independently identified by Shubnikov-de Haas oscillations as a vanishing Fermi surface cross section at k z = 0. Additionally, we find that the violation of Kohler's rule allows a distinct insight into the temperature evolution of the observed quantum magnetoresistance effects. Recently, Dirac's matrix equation of relativistic electrons [1] has been found to be profoundly linked to the dynamics of electrons in solids. Application of this formalism has been proven key in describing the intertwined (pseudo)spin degrees of freedom [2][3][4]. One striking experimental implication of the linear dispersion is that in laboratory magnetic fields, it significantly enlarges low-index Landau level energy separations compared to parabolic bands generated by a comparable tight-binding transfer integral, making emergent Dirac fermion systems an ideal platform to study quantum Landau level effects. Observations of this range from the discovery of Shubnikov-de Haas (SdH) oscillations in elemental bismuth [5] to the first report of the quantum Hall effect at room temperature in graphene [6]. In this Rapid Communication we extend the quantum transport study of such Dirac structures to the critical point of a change in the bulk Fermi surface topology. From a semiclassical point of view, it is understood that magnetoresistance (MR) is sensitive to the topology of given Fermi surfaces [7]: The magnetic field B drives the electrons in orbits around the Fermi surface (FS), sensing its geometry and topology. Here we describe the effect of the Dirac structure in this context of Fermi surface topology, which we observe as a magnetoresistance effect of pure quantum origin across the bulk Dirac node.We study the system BiTeI that possesses a Dirac node generated by Rashba-type spin-orbit coupling α · (σ × k) [8,9], where α is the structure-specific Rashba parameter, and σ and k are the spin and momentum operators, respectively. This layered semiconductor breaks inversion symmetry by crystallizing in the polar space group P 3m1 so that the spin-orbit interaction takes the form of a Rashba term in the bulk three-dimensional (3D) band structure. This has been confirmed by angle-resolved photoemission spectroscopy [10] and relativistic ab initio calculations [11]. In this system, both the conduction band minimum and the valence band maximum are located near the A point in the hexagonal * Present address: Department of Physics, Massa...

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“…The most promising mechanism is based on the Rashba effect [3] and the subsequent spin precession induced in such systems [4]. While most research has previously focused on 2D electron systems [5,6], recently a threedimensional (3D) form of such Rashba effect was found in a series of bismuth tellurohalides BiTeX (X = I, Br, or Cl) [7][8][9][10][11][12]. Although these materials exhibit a very large spin splitting, they lack an important property concerning functionalization, namely, the possibility to switch or tune the spin texture.…”

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Disentangling bulk and surface Rashba effects in ferroelectricα-GeTe

Volfová²,

et al. 2016

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Macroscopic ferroelectric order in α-GeTe with its noncentrosymmetric lattice structure leads to a giant Rashba spin splitting in the bulk bands due to strong spin-orbit interaction. Direct measurements of the bulk band structure using soft x-ray angle-resolved photoemission (ARPES) reveals the three-dimensional electronic structure with spindle torus shape. By combining high-resolution and spin-resolved ARPES as well as photoemission calculations, the bulk electronic structure is disentangled from the two-dimensional surface electronic structure by means of surface capping, which quenches the complex surface electronic structure. This unravels the bulk Rashba-split states in the ferroelectric Rashba α-GeTe(111) semiconductor exhibiting a giant spin splitting with Rashba parameter α R around 4.2 eVÅ, the highest of so-far known materials. DOI: 10.1103/PhysRevB.94.205111 In spintronics an important goal is to be able to control the spin of the electron in solids without applying magnetic fields [1,2]. The most promising mechanism is based on the Rashba effect [3] and the subsequent spin precession induced in such systems [4]. While most research has previously focused on 2D electron systems [5,6], recently a threedimensional (3D) form of such Rashba effect was found in a series of bismuth tellurohalides BiTeX (X = I, Br, or Cl) [7][8][9][10][11][12]. Although these materials exhibit a very large spin splitting, they lack an important property concerning functionalization, namely, the possibility to switch or tune the spin texture. This limitation can be overcome in a new class of functional materials displaying Rashba splitting coupled to ferroelectricity, the so-called ferroelectric Rashba semiconductors (FERS) [13,14].Recent photoemission experiments on α-GeTe-the stable rhombohedral room temperature configuration of the GeTe phase change material [15]-indicate that this system is a hallmark candidate for entanglement of the ferroelectric and spin-orbit order [16,17]. Due to the giant Rashba splitting spin injection from magnetic systems into GeTe appears viable in order to achieve spin-to-charge conversion [18]. Therefore, ferroelectric [13] or multiferroic [19] Rashba semiconductors bring new multifunctional assets for spintronic devices. A crucial issue for the understanding of FERS is to disentangle the Rashba effect in the bulk caused by the bulk ferroelectric lattice distortion and surface effects arising from particular surface terminations and/or possible band bendings. This represents a major challenge for surface sensitive techniques such as angle-resolved photoemission (ARPES). For this reason up to now ARPES measurements on α-GeTe surfaces performed in the surface-sensitive UV regime have been dominated by surface effects [16,17] and clear information of the three-dimensional bulk electronic structure and its spin texture has not been obtained.

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Quantum oscillations and optical conductivity in Rashba spin-splitting BiTeI

Cited by 68 publications

References 15 publications

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

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

Transport signatures of Fermi surface topology change in BiTeI

Disentangling bulk and surface Rashba effects in ferroelectricα-GeTe

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