Strain‐Mediated Inverse Photoresistivity in SrRuO₃/La_0.7Sr_0.3MnO₃ Superlattices

Abstract

In the pursuit of novel functionalities by utilizing the lattice degree of freedom in complex oxide heterostructure, the control mechanism through direct strain manipulation across the interfaces is still under development, especially with various stimuli, such as electric fi eld, magnetic fi eld, light, etc. In this study, the superlattices consisting of colossal-magnetoresistive manganites La 0.7 Sr 0.3 MnO 3 (LSMO) and photostrictive SrRuO 3 (SRO) have been designed to investigate the light-dependent controllability of lattice order in the corresponding functionalities and rich interface physics. Two substrates, SrTiO 3 (STO) and LaAlO 3 (LAO), have been employed to provide the different strain environments to the superlattice system, in which the LSMO sublayers exhibit different orbital occupations. Subsequently, by introducing light, we can modulate the strain state and orbital preference of LSMO sublayers through light-induced expansion of SRO sublayers, leading to surprisingly opposite changes in photoresistivity. The observed photoresistivity decreases in the superlattice grown on STO substrate while increases in the superlattice grown on LAO substrate under light illumination. This work has presented a model system that demonstrates the manipulation of orbital-lattice coupling and the resultant functionalities in artifi cial oxide superlattices via light stimulus.

Giant Photoresponse in Quantized SrRuO3 Monolayer at Oxide Interfaces

“…Similar results for the 50 nm SRO thin film with a very small photoresistivity of ~ 0.2% to 2% can be obtained in our previous studies. [39][40] These observations support that only the opened small bandgap in the SRO monolayer can originate large photoresponse in this kind of oxide heterstructures. Therefore, further exploration of the photocurrent in the semiconducting SRO monolayer at the interface between the LAO layer and the STO substrate becomes very attractive.…”

“…Such a reduction of energy gap under illumination is possibly from the structural variation of the SRO monolayer due to the photostriction effect and photo-excited electrons accumulated at the interface. [39][40] Hence, the electronic conductivity of the SRO monolayer can be greatly enhanced under illumination.…”

Unconventional anomalous Hall effect driven by oxygen-octahedra-tailoring of the SrRuO3 structure

“…Further work on SrRuO 3 films interfaced to ferroelectric films with off-centering B-site distortions [12] and ferromagnetic films with strong mutual antiferromagnetic coupling [13] yielded similar signatures. However, since these kind of structures show complex strain states [14] and intricate oxygen octahedra rotation patterns [15], it is an open question whether the Hall effect signatures are truly a proof for the presence of skyrmions.…”

Optically and electrically co-controlled resistance switching in complex oxide heterostructures

“…For E ¼ 0 kV/cm, a stable and distinct light-induced enhancement of resistance (i.e., positive photoresistance of 0.066%) was observed, which is superior to earlier reports on SRO films. 33 This finding can be attributed to the visible-light-induced lattice expansion [see Fig. 4(b)] and the resulting decrease in the orbital overlap of the SRO films.…”