Interplay of Rashba/Dresselhaus spin splittings probed by photogalvanic spectroscopy –A review

Ganichev, Sergey; Golub, L. E.

doi:10.1002/pssb.201350261

Cited by 206 publications

(211 citation statements)

References 299 publications

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“…It can be created either by the injection of a spin-current or by optical excitation. [103][104][105][106] Both methods have been used in InAs and GaAs heterostructures to determine the relative amplitude of Rashba and Dresselhaus effects. 105 The MPGE uses a normal incident light excitation in addition to an in-plane magnetic field to generate the photocurrent (Figure 3-h).…”

Section: Characterization Of Rashba and Dresselhaus Couplingsmentioning

confidence: 99%

“…The CPGE (Figure 3f) uses a circularly polarized light to generate an unbalanced occupation in momentum space of the excited carriers because of the band splitting and spin textures induced by the Rashba and/or Dresselhaus effects. [101][102][103] In the SGE (Figure 3-g), the electric current is caused by the out-of-equilibrium spin polarization of the system. It can be created either by the injection of a spin-current or by optical excitation.…”

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Rashba and Dresselhaus Couplings in Halide Perovskites: Accomplishments and Opportunities for Spintronics and Spin–Orbitronics

Képénékian

Even

2017

J. Phys. Chem. Lett.

174

181

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In halide hybrid organic-inorganic perovskites (HOP), spin-orbit coupling (SOC) presents a well-documented large influence on band structure. However, SOC may also present more exotic effects, such as Rashba and Dresselhaus couplings. In this perspective, we start by recalling the main features of this effect and what makes HOP materials ideal candidates for the generation and tuning of spin-states. Then, we detail the main spectroscopy techniques able to characterize these effects and their application to HOP. Finally, we discuss potential applications in spintronics and in spin-orbitronics in those non-magnetic systems, that would complete the skill set of HOP and perpetuate its ride on the crest of the wave of popularity started with optoelectronics and photovoltaics. Graphical TOC EntryPage 2 of 29 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A c c e p t e d m a n u s c r i p tThe continuous success of halide hybrid organic-inorganic perovskites (HOP) as solar cell active materials follows several paths. The main activity after 2012 consisted in the search for improvement of the power conversion efficiency (PCE) in typical laboratory configuration (small area, controlled environment). It led to an unprecedented growth of the PCE that has repeatedly reached record values over 22%. 1,2 Meanwhile, another branch of HOP studies have been focused on improving the stability of those cells unfortunately sensitive to light and moisture. 3,4 Opting for various mixtures of halide and cations, 2 various forms, e.g. layered HOP, [5][6][7] or by encapsulating the materials, the stability went from few hours to several thousands hours. Encouraged by these breakthroughs, a third path has pushed the area of hight performance solar cells from less than 1 cm 2 up to 50 cm 2 with a PCE of 12.6%, 8 bringing the perovskite solar cells even closer to commercial use.A common point to all these record HOP materials is the presence of lead. Even though a large effort has been and still is dedicated to the search for efficient lead-free HOP materials, 9,10 their current record PCE remains around 6.4%. 11 It is certainly unfortunate for solar cells because of the known toxicity of lead, 12 even though solutions have early been proposed, 13,14 however, due to the large spin-orbit coupling (SOC) exhibited by Pb, it represents a great opportunity for optoelectronics, spintronics and spin-orbitronics applications where undesired heavy elements can find a place (e.g. arsenic, cadmium).The first identified effect of SOC in HOP materials has been a surprising giant splitting of conduction bands, 15,16 instead of the usual valence band splitting observed in classical semiconductors. 17 It has a strong influence on the band gap energy as well as on the effective masses and the oscillator strength of the optical transitions at the band gap. The chan...

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Section: Characterization Of Rashba and Dresselhaus Couplingsmentioning

confidence: 99%

mentioning

confidence: 99%

Rashba and Dresselhaus Couplings in Halide Perovskites: Accomplishments and Opportunities for Spintronics and Spin–Orbitronics

Képénékian

Even

2017

J. Phys. Chem. Lett.

174

181

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“…We show that the excitation causes an imbalance in the electron distribution between positive and negative wave vectors. This is probed as the associated photogalvanic [14,15] current, which reverses its direction upon switching the helicity.…”

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Photogalvanic probing of helical edge channels in two-dimensional HgTe topological insulators

et al. 2017

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We report on the observation of a circular photogalvanic current excited by terahertz laser radiation in helical edge channels of two-dimensional (2D) HgTe topological insulators (TIs). The direction of the photocurrent reverses by switching the radiation polarization from a right-handed to a left-handed one and, for fixed photon helicity, is opposite for the opposite edges. The photocurrent is detected in a wide range of gate voltages. With decreasing the Fermi level below the conduction band bottom, the current emerges, reaches a maximum, decreases, changes its sign close to the charge neutrality point (CNP), and again rises. Conductance measured over a ≈3 μm distance at CNP approaches 2e 2 /h, the value characteristic for ballistic transport in 2D TIs. The data reveal that the photocurrent is caused by photoionization of helical edge electrons to the conduction band. We discuss the microscopic model of this phenomenon and compare calculations with experimental data. DOI: 10.1103/PhysRevB.95.201103 The quantum spin Hall (QSH) effect occurs in 2D TIs and rests on the existence of conducting helical edge states while the bulk is insulating [1][2][3][4]. In contrast to the quantum Hall effect, the formation of these edge states requires no magnetic field: they stem from the band inversion caused by strong spin-orbit interaction and are topologically protected by time reversal symmetry. Given that the spin-up and spin-down electrons propagate along an edge in opposite directions, i.e., the spin projection is locked to the k vector, the edge channels are helical in nature. The first experimental evidence for the QSH effect was obtained in HgTe quantum wells (QWs) [5] by observing a resistance plateau around h/2e 2 in the longitudinal resistance of a mesoscopic Hall bar. Here h is Planck's constant and e is the electron charge. This observation was further confirmed by nonlocal experiments in the ballistic [6] and diffusive [7] transport regime. Conducting edge channels were later probed by scanning SQUID microscopy [8], scanning gate microscopy [9], microwave impedance microscopy [10], and by analyzing supercurrents [11]. The spin polarization of the edge states was investigated so far by electrical means only: by detecting the spin to charge conversion in devices utilizing the inverse spin Hall effect [12] or with ferromagnetic contacts [13].Here we use circularly polarized terahertz radiation to excite selectively spin-up and spin-down electrons circling clockwise and counterclockwise around a sample. We show that the excitation causes an imbalance in the electron distribution between positive and negative wave vectors. This is probed as the associated photogalvanic [14,15] current, which reverses its direction upon switching the helicity.The experiments have been carried out on Hg 0.3 Cd 0.7 Te/HgTe/Hg 0.3 Cd 0.7 Te single QW structures with a well width of 8 nm having inverted band ordering. We used this width to maximize the energy gap to about 25 meV [4,5]. Structures were grown by molecular beam epitaxy o...

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“…14,15 Such a spatial mapping of the spin mode allows the determination of the SO parameters, but requires a spatial resolution better than the SO length. Photogalvanic effects 16 are sensitive to the ratio of the Rashba and the Dresselhaus field but require electric contacts to the 2DEG. Here, we introduce an optical method for characterizing SO fields that does not require electric contacts, works with arbitrary ratios of Rashba and Dresselhaus SO fields, and needs only modest spatial resolution where spot sizes may be larger than the SO length.…”

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confidence: 99%

All-optical evaluation of spin-orbit interaction based on diffusive spin motion in a two-dimensional electron gas

Kohda

Altmann

Schuh

et al. 2015

Applied Physics Letters

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Interplay of Rashba/Dresselhaus spin splittings probed by photogalvanic spectroscopy –A review

Cited by 206 publications

References 299 publications

Rashba and Dresselhaus Couplings in Halide Perovskites: Accomplishments and Opportunities for Spintronics and Spin–Orbitronics

Rashba and Dresselhaus Couplings in Halide Perovskites: Accomplishments and Opportunities for Spintronics and Spin–Orbitronics

Photogalvanic probing of helical edge channels in two-dimensional HgTe topological insulators

All-optical evaluation of spin-orbit interaction based on diffusive spin motion in a two-dimensional electron gas

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