Controlled formation of high-mobility shallow electron gases in SrTiO<sub>3</sub>single crystal

Chang, Jiang; Lee, Joon Sung; Lee, Tae Ho; Kim, Jinhee; Doh, Yong-Joo

doi:10.7567/apex.8.055701

Cited by 9 publications

(7 citation statements)

References 29 publications

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“…In particular, charge trapping by oxygen vacancies ( V O ) 9 and vacancy-related magnetism 10 – 13 are pertinent to the present study. Pristine STO develops oxygen vacancies when grown or annealed under oxygen-poor conditions 14 , bombarded with noble gas ions 15 , or under intense laser or ultraviolet irradiation 16 . When in numbers, V O can lead to the formation of two-dimensional electron gas (2DEG) on the surface of bare STO 17 – 20 .…”

Section: Introductionmentioning

confidence: 99%

Mechanical dissipation from charge and spin transitions in oxygen-deficient SrTiO3 surfaces

et al. 2018

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Bodies in relative motion separated by a gap of a few nanometers can experience a tiny friction force. This non-contact dissipation can have various origins and can be successfully measured by a sensitive pendulum atomic force microscope tip oscillating laterally above the surface. Here, we report on the observation of dissipation peaks at selected voltage-dependent tip-surface distances for oxygen-deficient strontium titanate (SrTiO3) surface at low temperatures (T = 5 K). The observed dissipation peaks are attributed to tip-induced charge and spin state transitions in quantum-dot-like entities formed by single oxygen vacancies (and clusters thereof, possibly through a collective mechanism) at the SrTiO3 surface, which in view of technological and fundamental research relevance of the material opens important avenues for further studies and applications.

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Section: Introductionmentioning

confidence: 99%

Mechanical dissipation from charge and spin transitions in oxygen-deficient SrTiO3 surfaces

et al. 2018

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“…The 2DEG can be also formed at the surfaces of transitional metal oxides [16][17][18] , which exhibits extraordinary properties such as tunable insulator-metal transitions 19 , large anisotropic magnetoresistance 20 , etc.. Due to the asymmetric geometry, the Rashba SO coupling is anticipated. Evidence of the Rashba spin splitting in the quasi 2DEG formed at the (001) surface of SrTiO 3 (STO) single crystal was found from weak localization or antilocalization analysis of the low-temperature magnetoresistance 7 .…”

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confidence: 99%

Spin galvanic effect at the conducting SrTiO3 surfaces

Zhang

Wang

Peng

et al. 2016

Applied Physics Letters

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The (001) surface of SrTiO3 were transformed from insulating to conducting after Ar+ irradiation, producing a quasi two-dimensional electron gas (2DEG). This conducting surface layer can introduce Rashba spin orbital coupling due to the broken inversion symmetry normal to the plane. The spin splitting of such a surface has recently been demonstrated by magneto-resistance and angular resolved photoemission spectra measurements. Here we present experiments evidencing a large spin-charge conversion at the surface. We use spin pumping to inject a spin current from NiFe film into the surface, and measure the resulting charge current. The results indicate that the Rashba effect at the surface can be used for efficient charge-spin conversion, and the large efficiency is due to the multi-d-orbitals and surface corrugation. It holds great promise in oxide spintronics.Comment: 11 pages, 5 figure

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“…In most cases, the linear MR-H behaviors might be obtained with the magnetic field parallel to the electric field. [35][36][37] For our samples, the fabrication method determines the vertical structure of the p-n junction with built-in and external electric field parallel to the magnetic field. For comparison, Figure 2d In order to clarify the effect of light on MR, the transition from PMR to NMR is illustrated by decreasing light power density in Figure 3a.…”

Section: Resultsmentioning

confidence: 99%

Rewritable Optical Memory Based on Sign Switching of Magnetoresistance

Liu

Lü

et al. 2019

Adv Elect Materials

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structure and lattice defects, whereas magnetic phenomena derive from spintronic characteristics and dynamics of charge carriers. [1,4-6] To be sure, coupling between optical and magnetic effects is well known through the Kerr and Faraday effects. [7,8] Recent advances of light-induced magnetization and light-controlled spin current have drawn extensive interest for promising applications of optical memory devices. [9,10] Light-controlled magnetism has been observed principally in magnetic materials. [11-14] It is also of interest for non-magnetic materials, for which incident photons tend to control the spin polarization, possibly causing a modulation in magnetoresistance (MR). [15,16] A worthwhile goal is to utilize photon energy to gain control of magnetic states, thus utilizing the storage feature of magnetic phenomena to achieve memory of optical signals. This strategy is expected to lead to optospintronic devices, [17] by combining the advantages of optical and magnetic characteristics. Compared with the traditional ferromagnetic memory devices, the direct storage of optical signals in optical memory devices is promising for applications in existing network systems, [18] especially when considering that the information transmission is almost always performed through optical fibers. Without extra signal conversions, the optical memory devices may decrease the loss of optical signals and enhance the efficiency of information transmission. Although much research has been reported on the optical control of spin current in non-magnetic materials, [15-17,19] few studies investigated the light-induced sign switching between positive magnetoresistance (PMR) and negative magnetoresistance (NMR). PMR occurs when electrical resistance increases as an applied external magnetic field increases; NMR is an opposite phenomenon-a decreasing resistance as magnetic field increases. NMR is usually caused by spindependent scattering or a magnetic-field-induced phase transition. [2,3] Generally, most materials show PMR effect due to Lorentz force. [20] In non-magnetic materials, the NMR effect is very rare and often depends on specific physical mechanisms, including strain effect, electrical gating, chiral anomaly in Weyl semimetals, and so on. [21-23] Exploring the light-induced NMR effect in non-magnetic systems may advance a physical understanding of optospintronics and provide a new route toward optical memory devices based on MR switching.

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Controlled formation of high-mobility shallow electron gases in SrTiO₃single crystal

Cited by 9 publications

References 29 publications

Mechanical dissipation from charge and spin transitions in oxygen-deficient SrTiO3 surfaces

Mechanical dissipation from charge and spin transitions in oxygen-deficient SrTiO3 surfaces

Spin galvanic effect at the conducting SrTiO3 surfaces

Rewritable Optical Memory Based on Sign Switching of Magnetoresistance

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Controlled formation of high-mobility shallow electron gases in SrTiO3single crystal

Cited by 9 publications

References 29 publications

Mechanical dissipation from charge and spin transitions in oxygen-deficient SrTiO3 surfaces

Mechanical dissipation from charge and spin transitions in oxygen-deficient SrTiO3 surfaces

Spin galvanic effect at the conducting SrTiO3 surfaces

Rewritable Optical Memory Based on Sign Switching of Magnetoresistance

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Controlled formation of high-mobility shallow electron gases in SrTiO₃single crystal