Strain-enhanced giant Rashba spin splitting in ultrathin KTaO<sub>3</sub> films for spin-polarized photocurrents

Wu, Ning; Zhang, Xue‐Jing; Liu, Bang-Gui

doi:10.1039/d0ra08745a

Cited by 9 publications

(7 citation statements)

References 59 publications

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“…It is known that the strain can induce both the bulk and structure inversion asymmetries, which can give rise to the Dresselhaus and Rashba spin-orbit interaction induced momentum (k)-dependent spin splitting. [65][66][67][68][69][70][71] In our case, since the lattice strain in the Cd 3 As 2 films is maximal near the interface with the GaAs substrate, and relaxes gradually with the increase of thickness, implying that there exists a strain gradient in our samples. The thinner the film, the larger the strain gradient will be expected.…”

Section: Resultsmentioning

confidence: 65%

Strain-induced circular photogalvanic current in Dirac semimetal Cd₃As₂ films epitaxied on a GaAs(111)B substrate

Liang

Zhai

et al. 2022

Nanoscale

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Section: Resultsmentioning

confidence: 65%

Strain-induced circular photogalvanic current in Dirac semimetal Cd₃As₂ films epitaxied on a GaAs(111)B substrate

Liang

Zhai

et al. 2022

Nanoscale

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“…Bareille et al [185] observed a 2DEG at the (111) surface of KTO, confined to the (111) bilayer of Ta atoms, which form a honeycomb lattice in this plane. The ARPES measurements showed only one sub-band with the effective mass m* = 0.3m e , which was taken to imply that the 2DEG was formed by itinerant conduction electrons confined to the reconstructed subsurface layers.…”

Section: Band Structure Modification Due To Surface Conductivity: Arp...mentioning

confidence: 99%

KTaO₃—The New Kid on the Spintronics Block

Gupta¹,

Harsha²,

Kumari³

et al. 2022

Advanced Materials

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Long after the heady days of high‐temperature superconductivity, the oxides came back into the limelight in 2004 with the discovery of the 2D electron gas (2DEG) in SrTiO3 (STO) and several heterostructures based on it. Not only do these materials exhibit interesting physics, but they have also opened up new vistas in oxide electronics and spintronics. However, much of the attention has recently shifted to KTaO3 (KTO), a material with all the “good” properties of STO (simple cubic structure, high mobility, etc.) but with the additional advantage of a much larger spin‐orbit coupling. In this state‐of‐the‐art review of the fascinating world of KTO, it is attempted to cover the remarkable progress made, particularly in the last five years. Certain unsolved issues are also indicated, while suggesting future research directions as well as potential applications. The range of physical phenomena associated with the 2DEG trapped at the interfaces of KTO‐based heterostructures include spin polarization, superconductivity, quantum oscillations in the magnetoresistance, spin‐polarized electron transport, persistent photocurrent, Rashba effect, topological Hall effect, and inverse Edelstein Effect. It is aimed to discuss, on a single platform, the various fabrication techniques, the exciting physical properties and future application possibilities of this family of materials.

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“…For KTO(001) thin films, there are large Rashba energy splitting due to the spin-orbit coupling (SOC) in Ta-5d xz and 5d yz bands, but the SOC has little effect on Ta-5d xy bands [14,37]. Here, the 2DEG consists of Ta-5d xy states and the 2DHG O-2p x /p y states, and therefore the SOC effect is little on electronic structures of the 2DEG and 2DHG.…”

Section: B Interfacial 2d Electron and Hole Gasesmentioning

confidence: 99%

Coexisting two-dimensional electron and hole gases highly confined at the interfaces of undoped KTaO3-sandwiching heterostructures

Wu¹,

Liu²

2022

Preprint

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Two-dimensional electron gas (2DEG) in interfaces and surfaces based on perovskite SrTiO3 (STO) has exhibited various interesting phenomena and is used to develop oxide electronics. Recently, KTaO3 (KTO) shows great potential and is believed to host more exciting effects and phenomena toward novel devices. Here, through first-principles investigation and analysis, we find two types of coexisting 2DEG and 2D hole gas (2DHG) highly confined at the interfaces in undoped STO/KTO/BaTiO3 heterostructures, when the KTO thickness m reaches a crititcal value. The two interfaces are made by (SrO) 0 /(TaO2) + and (KO) − /(TiO2) 0 for the A-type, and by (TiO2) 0 /(KO) − and (TaO2) + /(BO) 0 for the B-type. The 2D electron carriers originate from Ta-5dxy states at the interface including TaO2 atomic layer, and the hole carriers from O-2px/py orbitals at the other interface. The electron and hole effective masses are 0.3m0 and 1.06 ∼ 1.12m0, respectively, where m0 is mass of free electron, and the 2D carrier concentrations are in the order of 10 13 cm −2 . Our analysis indicates that the interfacial 2DEG and 2DHG are simultaneously formed because of the band bending due to the polar discontinuity at the interfaces and the stress-induced polarization within the KTO layer. These could stimulate more exploration for new phenomena and novel devices.

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Strain-enhanced giant Rashba spin splitting in ultrathin KTaO₃ films for spin-polarized photocurrents

Abstract: Strong Rashba effects at semiconductor surfaces and interfaces have attracted attention for exploration and applications. We show with first-principles investigation that applying biaxial stress can cause tunable and giant Rashba effects in ultrathin KTaO3 (KTO) (001) films.

Cited by 9 publications

References 59 publications

Strain-induced circular photogalvanic current in Dirac semimetal Cd₃As₂ films epitaxied on a GaAs(111)B substrate

Strain-induced circular photogalvanic current in Dirac semimetal Cd₃As₂ films epitaxied on a GaAs(111)B substrate

KTaO₃—The New Kid on the Spintronics Block

Coexisting two-dimensional electron and hole gases highly confined at the interfaces of undoped KTaO3-sandwiching heterostructures

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Strain-enhanced giant Rashba spin splitting in ultrathin KTaO3 films for spin-polarized photocurrents

Abstract: Strong Rashba effects at semiconductor surfaces and interfaces have attracted attention for exploration and applications. We show with first-principles investigation that applying biaxial stress can cause tunable and giant Rashba effects in ultrathin KTaO3 (KTO) (001) films.

Cited by 9 publications

References 59 publications

Strain-induced circular photogalvanic current in Dirac semimetal Cd3As2 films epitaxied on a GaAs(111)B substrate

Strain-induced circular photogalvanic current in Dirac semimetal Cd3As2 films epitaxied on a GaAs(111)B substrate

KTaO3—The New Kid on the Spintronics Block

Coexisting two-dimensional electron and hole gases highly confined at the interfaces of undoped KTaO3-sandwiching heterostructures

Contact Info

Product

Resources

About

Strain-enhanced giant Rashba spin splitting in ultrathin KTaO₃ films for spin-polarized photocurrents

Strain-induced circular photogalvanic current in Dirac semimetal Cd₃As₂ films epitaxied on a GaAs(111)B substrate

Strain-induced circular photogalvanic current in Dirac semimetal Cd₃As₂ films epitaxied on a GaAs(111)B substrate

KTaO₃—The New Kid on the Spintronics Block