Phase diagram of electrostatically doped Strontium Titanate (SrTiO3)

TL;DR

This study explores how electrostatic doping of SrTiO3 using ionic liquids affects its electronic phases, revealing a transition from insulator to superconductor with potential magnetic ordering near the boundary.

Contribution

It provides the first broad-range phase diagram of electrostatically doped SrTiO3, highlighting carrier-density dependent transitions and possible magnetic order.

Findings

Observation of a conductor-insulator transition with increasing doping

Detection of anomalous Hall effect indicating magnetic ordering

Emergence of superconductivity at high carrier densities

Abstract

Electric double layer transistor configurations have been employed to electrostatically dope single crystals of insulating SrTiO_{3}. Here we report on the results of such doping over broad ranges of temperature and carrier concentration employing an ionic liquid as the gate dielectric. The surprising results are, with increasing carrier concentration, an apparent carrier-density dependent conductor-insulator transition, a regime of anomalous Hall effect, suggesting magnetic ordering, and finally the appearance of superconductivity. The possible appearance of magnetic order near the boundary between the insulating and superconducting regimes is reminiscent of effects associated with quantum critical behavior in some complex compounds.