Electrolyte gate-controlled Kondo effect in SrTiO3

TL;DR

This study demonstrates the electric field control of the Kondo effect in SrTiO3 using ionic gel gating, revealing the interplay between localized magnetic moments and conduction electrons in a 2D electron system.

Contribution

It provides the first direct evidence of gate-tunable Kondo effect in SrTiO3, linking ionic gel gating to magnetic impurity behavior in oxide interfaces.

Findings

Observation of resistance upturn and negative magnetoresistance at high gate voltages

Identification of localized Ti3+ magnetic moments coexisting with conduction electrons

Electric field effectively tunes the Kondo effect in SrTiO3

Abstract

We report low-temperature, high-field magnetotransport measurements of SrTiO3 gated by an ionic gel electrolyte. A saturating resistance upturn and negative magnetoresistance that signal the emergence of the Kondo effect appear for higher applied gate voltages. This observation, enabled by the wide tunability of the ionic gel-applied electric field, promotes the interpretation of the electric field-effect induced 2D electron system in SrTiO3 as an admixture of magnetic Ti3+ ions, i.e. localized and unpaired electrons, and delocalized electrons that partially fill the Ti 3d conduction band.