Electric-field-induced superconductivity in an insulator

Abstract

Electric field control of charge carrier density has long been a key technology to tune the physical properties of condensed matter, exploring the modern semiconductor industry. One of the big challenges is to increase the maximum attainable carrier density so that we can induce superconductivity in field-effect-transistor geometry. However, such experiments have so far been limited to modulation of the critical temperature in originally conducting samples because of dielectric breakdown. Here we report electric-field-induced superconductivity in an insulator by using an electric-double-layer gating in an organic electrolyte. Sheet carrier density was enhanced from zero to 10(14) cm(-2) by applying a gate voltage of up to 3.5 V to a pristine SrTiO(3) single-crystal channel. A two-dimensional superconducting state emerged below a critical temperature of 0.4 K, comparable to the maximum value for chemically doped bulk crystals, indicating this method as promising for searching for unprecedented superconducting states.

Direct Imaging of Nanoscale Conductance Evolution in Ion-Gel-Gated Oxide Transistors

“…Such unprecedented tunability of electron concentration represents a paradigm shift in condensed matter physics research since many carrier-mediated processes, previously only accessible through chemical substitution, can now be studied in the FET configuration with better controllability and less disorder effect 13,14 . To date, the EDLT structure has been utilized to investigate the field-induced MITs 12,[15][16][17] , magnetic ordering 18,19 , interfacial superconductivity [20][21][22][23][24][25] , and topological surface states 19,26 in a variety of advanced materials, with an ever increasing list in the foreseeable future.…”

Two-dimensional electron gas at the LaAlO3/SrTiO3 inteface with a potential barrier

“…This is because interfaces between two oxides may have unusual properties. [1][2][3] It has been shown, that even though the constituent oxides are ordinary band insulators with well-known electronic properties, 4 their interfaces can exhibit a variety of phenomena -from two-dimensional (2D) metallic conductivity, [5][6][7][8][9] and superconductivity, 10 to ferromagnetism 11,12 and coexistence of magnetic order and superconductivity. 1,13,14 Beginning with the paper by Ohtomo and Hwang, 5 the physical properties of the LaAlO 3 /SrTiO 3 interface have been intensively studied in recent years, both experimentally and theoretically.…”

Theory of Multi-Orbital Superconductivity in SrTiO3/LaAlO3Interface

“…For instance, electron gases with a high carrier density on the order of 10 13 cm −2 have been realized in SrTiO 3 /LaAlO 3 (STO/LAO) interfaces [1], and SrTiO 3 (STO) surfaces [2]. The discovery of superconductivity [3], ferromagnetism [4][5][6], and their coexistence [5,6] shed light on innovating phenomena in these systems.…”

“…The discovery of superconductivity [3], ferromagnetism [4][5][6], and their coexistence [5,6] shed light on innovating phenomena in these systems. These quantum condensed phases are controlled by a gate voltage through the change of carrier density [2,7,8]. One of the key issues is the role of Rashbatype antisymmetric spin-orbit coupling [9] arising from the interfacial breaking of mirror symmetry, which may realize an exotic quantum condensed phase, such as non-centrosymmetric superconductivity [10], chiral magnetism [11], and their coexistent phase.…”