Electrical control of emergent phenomena in oxide thin film heterostructures

Oxide thin films exhibit intriguing physical phenomena along with diverse functionalities as their structures and physical properties are strongly intertwined. Iontronics has recently emerged as a novel concept for electrically controlling the various properties of oxide thin films through ionic motion and arrangement [1-3]. Here, I present the suppression of octahedral tilting and altered magnetism in ferromagnetic SrRuO3 thin films via hydrogen spillover [4]. The film further shows the reversal of anomalous Hall effects, enabling a topological Hell effect-like hump signal through hydrogenation. Additionally, I demonstrate the first realization of the epitaxial growth of T-Nb2O5 thin films, featuring vertical 2D ionic transport channels [5]. These channels enable rapid Li-ion migration within the film, along with a colossal insulator-metal transition, where resistivity decreases by 11 orders of magnitude due to the electron population of the initially empty Nb 4d0 states. This study offers an intriguing pathway for controlling emergent physical phenomena in correlated oxide thin films via electric-fields.

[1] Y. Guan†, H. Han† et al., Annu. Rev. Mater. Res. 53, 25-51 (2023).

[2] H. Han et al., ACS Nano 16, 6206−6214 (2022).

[3] H. Han* et al., Proc. Nat. Acad. Sci. USA. (PNAS) 120, e2221651120 (2023).

[4] H. Han* et al., Adv. Mater. 35, 2207246 (2023).

[5] H. Han* et al., Nat. Mater. 22, 1128-1135 (2023).