Two-dimensional normal-state quantum oscillations in a superconducting heterostructure

Abstract

Semiconductor heterostructures provide an ideal platform for studying high-mobility, low-density electrons in reduced dimensions. The realization of superconductivity in heavily doped diamond, silicon, silicon carbide and germanium suggests that Cooper pairs eventually may be directly incorporated in semiconductor heterostructures, but these newly discovered superconductors are currently limited by their extremely large electronic disorder. Similarly, the electron mean free path in low-dimensional superconducting thin films is usually limited by interface scattering, in single-crystal or polycrystalline samples, or atomic-scale disorder, in amorphous materials, confining these examples to the extreme 'dirty limit'. Here we report the fabrication of a high-quality superconducting layer within a thin-film heterostructure based on SrTiO(3) (the first known superconducting semiconductor). By selectively doping a narrow region of SrTiO(3) with the electron-donor niobium, we form a superconductor that is two-dimensional, as probed by the anisotropy of the upper critical magnetic field. Unlike in previous examples, however, the electron mobility is high enough that the normal-state resistance exhibits Shubnikov-de Haas oscillations that scale with the perpendicular field, indicating two-dimensional states. These results suggest that delta-doped SrTiO(3) provides a model system in which to explore the quantum transport and interplay of both superconducting and normal electrons. They also demonstrate that high-quality complex oxide heterostructures can maintain electron coherence on the macroscopic scales probed by transport, as well as on the microscopic scales demonstrated previously.

High‐Mobility Two‐Dimensional Electron Gas at InGaN/InN Heterointerface Grown by Molecular Beam Epitaxy

“…The deviation of the magneto‐transport traces between 0.1 and 0.15 1/ T mainly results from two aspects: 1) the β peak shape slightly changes with increasing temperature and, 2) the β peak is partially overlapped with the side peaks (γ peak and α peak) rather than being a completely independent peak. The related works reported by other groups also show similar behavior over the IFFT 5. The most essential issue is that the magneto‐transport traces for different temperatures can match well with the oscillation peak.…”

“…For decades, 2D electron gas (2DEG) systems have led to important experimental discoveries1, 2, 3, 4, 5, 6, 7 and conceptual developments for high‐speed and high‐power electronics 8, 9. Therefore, searching for materials to host 2DEG has become a key area of research 10, 11.…”

Electric field modulation of the tetragonal domain orientation revealed in the magnetic ground state of quantum paraelectric EuTiO3

“…Their dielectric and transport properties are easily modulated by epitaxial strain, field-effect or chemical doping [1][2][3][4] , hence facilitating their integration with conventional charge-based electronics. However, the past decade has also seen an intensive search for a multiferroic perovskite with strong magnetoelectric coupling, which would enjoy numerous spintronic applications.…”

Superconductivity above 100 K in single-layer FeSe films on doped SrTiO3

“…with the earlier work on superconducting oxides interfaces [3][4][5][6] , demonstrates that interface between two different materials provide not only a rich system for studying two-dimensional (2D) superconductivity, but also a potential pathway to high-T c superconductivity [7][8][9][10][11][12] .…”