Reversible manipulation of the magnetic state in SrRuO<sub>3</sub> through electric-field controlled proton evolution.

Li, Zhuolu; Shen, Shengchun; Tian, Zijun; Hwangbo, Kyle; Wang, Meng; Wang, Yujia; Bartram, F Michael; He, Liqun et al. · Nat Commun · 2020

basic_science · Level V

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Abstract

Ionic substitution forms an essential pathway to manipulate the structural phase, carrier density and crystalline symmetry of materials via ion-electron-lattice coupling, leading to a rich spectrum of electronic states in strongly correlated systems. Using the ferromagnetic metal SrRuO<sub>3</sub> as a model system, we demonstrate an efficient and reversible control of both structural and electronic phase transformations through the electric-field controlled proton evolution with ionic liquid gating. The insertion of protons results in a large structural expansion and increased carrier density, leading to an exotic ferromagnetic to paramagnetic phase transition. Importantly, we reveal a novel protonated compound of HSrRuO<sub>3</sub> with paramagnetic metallic as ground state. We observe a topological Hall effect at the boundary of the phase transition due to the proton concentration gradient across the film-depth. We envision that electric-field controlled protonation opens up a pathway to explore novel electronic states and material functionalities in protonated material systems.