Dual gate control of bulk transport and magnetism in the spin-orbit insulatorSr2IrO4

Abstract

Abstracts: The 5d iridates have been the subject of much recent attention due to the predictions of a large array of novel electronic phases driven by twisting strong spin-orbit coupling and Hubbard correlation. As a prototype, the single layered perovskite Sr 2 IrO 4 was first revealed to host a J eff =1/2 Mott insulating state. In this material, the approximate energy scale of a variety of interactions, involving spin-orbit coupling, magnetic exchange interaction, and the Mott gap, allows close coupling among the corresponding physical excitations, opening the possibility of cross control of the physical properties. Here, we experimentally demonstrate the effective gate control of both the transport and magnetism in a Sr 2 IrO 4 -based field effect transistor using an ionic liquid dielectric. This approach could go beyond the surface-limited field effect seen in conventional transistors, reflecting the unique aspect of the J eff =1/2 state. The simultaneous modulation of conduction and magnetism confirms the proposed intimate coupling of charge, orbital, and spin degrees of freedom in this oxide. These phenomena are probably related to an enhanced deviation from the ideal J eff =1/2 state due to the gate-promoted conduction. The present work would have important implications in modelling the unusual physics enabled by strong spin-orbit coupling, and provides a new route to explore those emergent quantum phases in iridates.

Endeavor of Iontronics: From Fundamentals to Applications of Ion‐Controlled Electronics

“…After the successful demonstration of electric‐field‐induced superconductivity in SrTiO 3 by EDLTs, many researchers have applied EDLTs to strongly correlated electron systems and demonstrated electrical switching of the MIT by an external voltage in a broad range of materials, including transition‐metal oxides and transition‐metal dichalcogenides . In this section, in particular, we focus on the results of EDLTs based on vanadium dioxide, VO 2 , perovskite manganite, Pr 0.5 Sr 0.5 MnO 3 , and tantalum disulfide, 1T‐TaS 2 , as representative examples of gate‐induced MITs in correlated insulators .…”

Magnetic and electronic properties of La3 MO7 and possible polaron formation in hole-doped La3 MO7 (M = Ru and Os)

“…Despite the change of nominal carrier density, surprisingly, this hope-doped system remain an insulator (or a semiconductor), violating the rigid band scenario [16]. Similar robust insulating behavior was also found in some doped iridates [17,18], which was expected to show superconductivity after doping [19,10].…”

“…However, till now, not only the superconductivity has not been found, but also there is an unsolved debate regarding the metallicity of doped Sr 2 IrO 4 . Some experiments reported the metallic transport behavior upon tiny doping and observed Fermi arcs using angle-resolved photoelectron spectroscopy (ARPES) [29,30,31,32], while some others reported robust insulating (or semiconducting) behavior even upon heavy doping by element substitution and field-effect gating [18,33].…”

Electrochemical oxygen intercalation into Sr2IrO4

“…In Ref. [15], an unexpected bulk gating effect for Sr 2 IrO 4 films as thick 40 nm was proposed, whereas conventional field effect is expected to be screened over a few nm, in the case of oxides with carrier density a few 10 20 cm À3 [39]. The field-induced carrier density exceeded by a factor 30 the one expected from the IL capacitance.…”

“…It is believed that doping should yield a particle-hole phase diagram similar to the one of the cuprates [7], including the possibility of a superconducting phase [8][9][10]. Thus, the stakes at doping the IrO 2 plane are high, and this was reported being done in several ways: chemical substitution [10][11][12][13], electric field effect [14,15], and oxygen stoichiometry [16]. However, the doping level obtained with these techniques is low: the field effect fails to reach a metallic state, while chemical substitution barely reach it, and is limited to 4-5%.…”