Electronic subbands in the a-LaAlO${}_3$/KTaO${}_3$ interface revealed by quantum oscillations in high magnetic fields

Abstract

Investigating Shubnikov-de Haas (SdH) oscillations in high magnetic fields, we experimentally infer the electronic band structure of the quasi-two-dimensional electron gas (2DEG) at the ionic-liquid gated amorphous (a)-LaAlO${}_3$/KTaO${}_3$ interface. The angular dependence of SdH oscillations indicates a 2D confinement of a majority of electrons at the interface. However, additional SdH oscillations with an angle-independent frequency observed at high tilt angles indicate the coexistence of 3D charge carriers extending deep into the KTaO${}_3$. The SdH oscillations measured in magnetic fields perpendicular to the interface show four frequencies corresponding to four 2D subbands with different effective masses (0.20 $m_e$ - 0.55 $m_e$). The single-frequency oscillations originating from 3D electrons yields a larger effective mass of $\sim$ 0.70 $m_e$. Overall, the inferred subbands are in good agreement with the theoretical-calculations and angle-resolved photoemission spectroscopy studies on 2DEG at KTaO${}_3$ surface.

References in corpus (22)

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• Coexistence of Magnetic Order and Two-dimensional Superconductivity at LaAlO${}_3$/SrTiO${}_3$ Interfaces
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• Coexistence of two- and three-dimensional Shubnikov-de Haas oscillations in Ar^+ -irradiated KTaO_3
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Cited by in corpus (8)

• Spontaneous rotational symmetry breaking in KTaO${}_3$ heterointerface superconductors
• Orientation-dependent electron-phonon coupling in interfacial superconductors LaAlO3/KTaO3
• Quantum oscillations in 2D electron gases with spin-orbit and Zeeman interactions
• Unconventional quantum oscillations and evidence of nonparabolic electronic states in quasi-two-dimensional electron system at complex oxide interfaces
• Spin-dependent anisotropic electron-phonon coupling in KTaO${}_3$
• Unique quantum metallic state in the titanium sesquioxide heterointerface superconductor
• Orientation-dependent superconductivity and electronic structure of the rare-earth metal/KTaO3 interfaces
• Absence of localized $5d^1$ electrons in KTaO${}_3$ interface superconductors