Two-dimensional superconductivity and anisotropic transport at KTaO
            <sub>3</sub>
            (111) interfaces

Liu, Changjiang; Yan, Xi; Jin, Dafei; Ma, Yang; Hsiao, Haw-Wen; Lin, Yulin; Bretz-Sullivan, Terence; Zhou, Xianjing; Pearson, John; Fisher, Brandon; Jiang, Juan; Han, Wei; Zuo, Jian‐Min; Wen, Jianguo; Fong, Dillon D.; Sun, Jinhe; Zhou, Hua; Bhattacharya, Anand

doi:10.1126/science.aba5511

Cited by 196 publications

(237 citation statements)

References 61 publications

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“…Liu et al, confirmed the results with the discovery of superconducting PLD grown interfaces between (111)-oriented KTaO 3 and insulating overlayers of LaAlO 3 [256]. It was found that the superconductivity of this heterostructure exhibits a crystallographic direction dependence in contrast to 2DEGs at SrTiO 3 interfaces [9,254,255] and can be continuously tuned from superconducting into insulating states by applying a gate voltage [257].…”

Section: Bilayersmentioning

confidence: 64%

Oxidic 2D Materials

Dubnack

Müller

2021

Materials

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The possibility of producing stable thin films, only a few atomic layers thick, from a variety of materials beyond graphene has led to two-dimensional (2D) materials being studied intensively in recent years. By reducing the layer thickness and approaching the crystallographic monolayer limit, a variety of unexpected and technologically relevant property phenomena were observed, which also depend on the subsequent arrangement and possible combination of individual layers to form heterostructures. These properties can be specifically used for the development of multifunctional devices, meeting the requirements of the advancing miniaturization of modern manufacturing technologies and the associated need to stabilize physical states even below critical layer thicknesses of conventional materials in the fields of electronics, magnetism and energy conversion. Differences in the structure of potential two-dimensional materials result in decisive influences on possible growth methods and possibilities for subsequent transfer of the thin films. In this review, we focus on recent advances in the rapidly growing field of two-dimensional materials, highlighting those with oxidic crystal structure like perovskites, garnets and spinels. In addition to a selection of well-established growth techniques and approaches for thin film transfer, we evaluate in detail their application potential as free-standing monolayers, bilayers and multilayers in a wide range of advanced technological applications. Finally, we provide suggestions for future developments of this promising research field in consideration of current challenges regarding scalability and structural stability of ultra-thin films.

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Section: Bilayersmentioning

confidence: 64%

Oxidic 2D Materials

Dubnack

Müller

2021

Materials

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“…All the arguments above go for these systems as well. Note that superconductivity found for KTaO 3 (111)/LaTiO 3 (111) and KTaO 3 (111)/EuO is strongly dependent on carrier density [65]. Besides, the absence of superconductivity in LaTiO 3 (100) related interfaces indicates the influence of larger polarity discontinuity in LaTiO 3 (111) related interfaces.…”

Section: Band Bending In Lao/stomentioning

confidence: 89%

“…LAO/STO provides a paradigmatic example for polar/nonpolar interface and similar polar/nonpolar oxide heterostructures are LaTiO 3 /STO [60], KTaO 3 /STO [61], LaVO 3 /STO [62], LMO/SrMnO 3 [63], KTaO 3 /EuO [64], KTaO 3 (111)/LaTiO 3 (111) [65] and KTaO 3 (111)/EuO [65]. All the arguments above go for these systems as well.…”

Section: Band Bending In Lao/stomentioning

confidence: 99%

Interface enhanced superconductivity in FeSe/SrTiO 3 and the hidden nature

Han¹,

Song²,

Ma³

et al. 2022

Comptes Rendus. Physique

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The superconductivity confined in a two-dimensional interface exhibits many exotic phenomena that have certain counterparts in layered cuprates and iron-based superconductors, and thus provides rare opportunities to reveal the mystery of high temperature superconductivity therein. By constructing and tailoring hybrid heterostructures such as FeSe/SrTiO 3 (FeSe/STO), interface-enhanced superconductivity arouses, and the substrate has been demonstrated to provide the phonons and enhance the strong electronphonon coupling (EPC) within monolayer FeSe. More research and reporting systems uncover that the bandbending induced charge transfer at the interface could become a unified microscopic picture to design the new interface superconductors. With re-examination of the experimental research in LaAlO 3 /STO (LAO/STO) and unconventional superconductors, the common characteristics such as band bending and rigid band shift are perceived in the FeSe/STO, LAO/STO and cuprate superconductors. This review may provide important information to inspect the mechanism of high-T c superconductivity from a different view.

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“…For perovskite KTaO 3 (KTO), some excellent properties have been observed, such as high mobilities and signatures of spin-orbit coupling in low-temperature magnetoresistance data [14], spin-charge conversion of 2DEG at KTO surface [15,16], spin-polarized 2DEGs at a mag- * Email: bgliu@iphy.ac.cn netic EuO/KTO interface [17], and 2D superconductivity discovered at the KTO-based oxide interfaces [18][19][20][21][22] (see [23] for an overall review). In view of realistic applications, a main challenge is the epitaxial growth of KTO because of very reactive potassium atoms.…”

Section: Introductionmentioning

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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Two-dimensional superconductivity and anisotropic transport at KTaO ₃ (111) interfaces

Cited by 196 publications

References 61 publications

Oxidic 2D Materials

Oxidic 2D Materials

Interface enhanced superconductivity in FeSe/SrTiO 3 and the hidden nature

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

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Two-dimensional superconductivity and anisotropic transport at KTaO 3 (111) interfaces

Cited by 196 publications

References 61 publications

Oxidic 2D Materials

Oxidic 2D Materials

Interface enhanced superconductivity in FeSe/SrTiO 3 and the hidden nature

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

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Product

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About

Two-dimensional superconductivity and anisotropic transport at KTaO ₃ (111) interfaces