The effect of fabrication conditions on 2DEGs transport characteristics at amorphous-LaAlO<sub>3</sub>/KTaO<sub>3</sub> interfaces

Zhang, Hui; Yan, Xi; Zhang, Jing; Zhang, Jine; Han, Furong; Huang, Hefei; Qi, Shaojin; Shi, Wenxiao; Shen, Baogen; Sun, J. R.

doi:10.1088/2053-1591/ab240a

Cited by 11 publications

(11 citation statements)

References 31 publications

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“…It is worth mentioning here that the a-LAO/KTO device ( O2 P = 1 × 10 −2 Torr) was highly insulating even before the IL gating process, consistent with the previous reports. [22] We, however, observed similar results before and the after IL gating effect on a-LAO/KTO device, for which a-LAO is grown at three other different O2 P (10 −3 , 10 −4 , 10 −5 Torr). The lower R s at low temperature after IL gating is most likely due to the decreasing of the density of oxygen vacancies, which act as scattering centers and cause the relatively high resistance before gating.…”

Section: Ionic-liquid Gatingsupporting

confidence: 74%

“…The lower R s at low temperature after IL gating is most likely due to the decreasing of the density of oxygen vacancies, which act as scattering centers and cause the relatively high resistance before gating. [22,30] A similar effect has also been reported for the 2DEG at the a-LAO/STO interface. [29] The striking influence of IL gating is evident in the Hall resistance variations, as shown in Figure 2b,c.…”

Section: Ionic-liquid Gatingsupporting

confidence: 69%

“…[13] As the origin of the electron gas is concerned, similar to STO-based interfaces, the origin of the 2DEG involves electrostatic relaxation and chemical reconstruction driven by the polar discontinuity, [3] interface chemistry, [18][19][20] and oxygen vacancies. [21,22] For a-LAO/KTO interface, the most likely scenario is the oxygen vacancies. In this scenario, the redox reaction at the interface, by oxidizing deposited LAO films and reducing the KTO substrate, accounts for the metallic interface.…”

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confidence: 99%

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Ionic Modulation at the LaAlO₃/KTaO₃ Interface for Extreme High‐Mobility Two‐Dimensional Electron Gas

Yan

Zeng

Rubi

et al. 2022

Adv Materials Inter

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The well-known and most widely explored oxide interface is the LaAlO 3 /SrTiO 3 (LAO/STO) heterointerface that was discovered in 2004 to exhibit high-mobility 2DEG, [3] and subsequently shown to reveal fascinating properties such as magnetism, superconductivity, and even coexistence of them. [4][5][6][7] Interestingly, the physical properties of the 2DEG at the LAO/STO interface are controllable through a back gate, [8] a top gate, [9] or an ionic liquid (IL) gate. [10] In particular, the electron mobility can be significantly enhanced by the IL gating, which triggers a switch of the 2DEG between a metallic and an insulating state. [11] To reveal the role of the Ti-ions to the emergent phenomena and obtain higher mobility 2DEG, many attempts to replace STO with other perovskite oxides have been made. [12,13] Among them, KTaO 3 (KTO), a polar and band-insulator (E g ≈ 3.6 eV) oxide, is particularly interesting. [13][14][15][16][17] Similar to STO, a 2DEG is realized at the metallic oxygen-deficient KTO surface [18] or the interface with other materials such as EuO/ KTO, [16] crystalline (c-) LaVO 3 /KTO, [15] amorphous (a-) LAO/ KTO, [15] and c-LaTiO 3 /KTO. [13] As the origin of the electron gas is concerned, similar to STO-based interfaces, the origin of the 2DEG involves electrostatic relaxation and chemical reconstruction driven by the polar discontinuity, [3] interface chemistry, [18][19][20] and oxygen vacancies. [21,22] For a-LAO/KTO interface, the most likely scenario is the oxygen vacancies. In this scenario, the redox reaction at the interface, by oxidizing deposited LAO films and reducing the KTO substrate, accounts for the metallic interface. Furthermore, the gate-tunable 2D superconductivity is exclusively reported for the KTO (111) and (110) based interfaces. [16,23] Intriguingly, the large Rashba coefficient extracted from the spin-charge and chargespin experiments makes KTO-2DEG a potential candidate for spin-orbitronic devices. [23] KTO is a 5d transition metal oxide that exhibits a lighter effective mass of electrons and a stronger spin-orbit coupling (SOC) at its conducting surface/interface than STO-based interfaces. As a result of strong SOC, the low-lying Ta:t 2g band splits at the Γ point and forms the light and heavy bands having the mixed character of d xy , d xz , and d yz orbitals. [18,24,25] Recent Due to the coexistence of many emergent phenomena, including 2D superconductivity and a large Rashba spin-orbit coupling, 5d transition metal oxides-based two-dimensional electron systems (2DESs) have been prospected as one of the potential intrants for modern electronics. However, despite the lighter electron mass, the mobility of carriers, a key requisite for high-performance devices, in 5d-oxides devices remains far behind their 3d-oxides analogs. The carriers' mobility in these oxides is significantly hampered by the inevitable presence of defects. Here, very high mobility (≈22 650 cm 2 V −1 s −1 ) of 5d-2DES confined at the LaAlO 3 /KTaO 3 interface is reported. The high mobility, which ...

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Section: Ionic-liquid Gatingsupporting

confidence: 74%

Section: Ionic-liquid Gatingsupporting

confidence: 69%

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confidence: 99%

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Ionic Modulation at the LaAlO₃/KTaO₃ Interface for Extreme High‐Mobility Two‐Dimensional Electron Gas

Yan

Zeng

Rubi

et al. 2022

Adv Materials Inter

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“…A careful optimization of the fabrication conditions (substrate temperature and oxygen pressure) for the LAO‐KTO thin films led to the observation of several emergent phenomena. [ 166 ] Lower temperatures and higher oxygen pressures favored higher metallicity of the interface. The value of the Fermi energy above which two types of charge carriers existed was also calculated.…”

Section: Low‐dimensional Electron Gas In Ktao3: Surfaces and Interfacesmentioning

confidence: 99%

“…They are also potentially interesting from the point of view of oxide electronics and spintronics. [45,46,166]…”

Section: Pulsed Laser Depositionmentioning

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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Two‐Dimensional Electron Gases at the Amorphous and Crystalline SrTiO₃/KTaO₃ Heterointerfaces

Gan

Zhao

et al. 2023

Physica Status Solidi (a)

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The 5d two‐dimensional electron gas (2DEG) based on KTaO3 (KTO) exhibits a lot of exotic properties such as stronger spin‐orbit coupling (SOC) and higher superconductivity transition temperature than those of SrTiO3 (STO)‐based 3d 2DEGs, whereas it has much lower electron mobility. Herein, the property of the 5d 2DEGs is investigated including the carrier mobility and Rashba SOC by interfacing both amorphous and crystalline STO with the crystalline KTO. Metallic 2DEGs are achieved at both interfaces of amorphous and crystalline STO‐capped KTO. Notably, the amorphous STO/KTO heterointerface has a larger carrier concentration and higher Hall mobility than the crystalline STO/KTO counterparts at low temperatures, which stems from two kinds of carriers. In contrast, the 5d 2DEG formed at the crystalline interface exhibits much stronger Rashba SOC as revealed through magnetotransport measurement. The deduced maximum strength of Rashba SOC and spin‐splitting energy are ≈8.56 × 10−12 eV m and ≈33.52 meV, respectively. Our results provide new insights on designing on‐demand properties of KTO‐based conducting interfaces.

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The effect of fabrication conditions on 2DEGs transport characteristics at amorphous-LaAlO₃/KTaO₃ interfaces

Cited by 11 publications

References 31 publications

Ionic Modulation at the LaAlO₃/KTaO₃ Interface for Extreme High‐Mobility Two‐Dimensional Electron Gas

Ionic Modulation at the LaAlO₃/KTaO₃ Interface for Extreme High‐Mobility Two‐Dimensional Electron Gas

KTaO₃—The New Kid on the Spintronics Block

Two‐Dimensional Electron Gases at the Amorphous and Crystalline SrTiO₃/KTaO₃ Heterointerfaces

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The effect of fabrication conditions on 2DEGs transport characteristics at amorphous-LaAlO3/KTaO3 interfaces

Cited by 11 publications

References 31 publications

Ionic Modulation at the LaAlO3/KTaO3 Interface for Extreme High‐Mobility Two‐Dimensional Electron Gas

Ionic Modulation at the LaAlO3/KTaO3 Interface for Extreme High‐Mobility Two‐Dimensional Electron Gas

KTaO3—The New Kid on the Spintronics Block

Two‐Dimensional Electron Gases at the Amorphous and Crystalline SrTiO3/KTaO3 Heterointerfaces

Contact Info

Product

Resources

About

The effect of fabrication conditions on 2DEGs transport characteristics at amorphous-LaAlO₃/KTaO₃ interfaces

Ionic Modulation at the LaAlO₃/KTaO₃ Interface for Extreme High‐Mobility Two‐Dimensional Electron Gas

Ionic Modulation at the LaAlO₃/KTaO₃ Interface for Extreme High‐Mobility Two‐Dimensional Electron Gas

KTaO₃—The New Kid on the Spintronics Block

Two‐Dimensional Electron Gases at the Amorphous and Crystalline SrTiO₃/KTaO₃ Heterointerfaces