Phase Instability amid Dimensional Crossover in Artificial Oxide Crystal

Abstract

Artificial crystals synthesized by atomic-scale epitaxy provides the ability to control the dimensions of the quantum phases and associated phase transitions via precise thickness modulation.In particular, reduction in dimensionality via quantized control of atomic layers is a powerful approach to revealing hidden electronic and magnetic phases. Here, we demonstrate a dimensionalitycontrolled and induced metal-insulator transition (MIT) in atomically designed superlattices by synthesizing a genuine two dimensional (2D) SrRuO3 crystal with highly suppressed charge transfer.The tendency to ferromagnetically align the spins in SrRuO3 layer diminishes in 2D as the interlayer exchange interaction vanishes, accompanying the 2D localization of electrons. Furthermore, electronic and magnetic instabilities in the two SrRuO3 unit cell layers induce a thermally-driven MIT along with a metamagnetic transition.

Observation of metallic electronic structure in a single-atomic-layer oxide

“…Based on this analogy, we chose a single-atomic-layer-thick SRO film (Fig. 1a) whose electronic ground state is currently under debate 27,28 . The monolayer SRO can be also regarded as a two-dimensional analog of a metallic single layer perovskite Sr 2 RuO 4 which has been intensively studied for its unconventional superconductivity 29 and recently for magnetism 30 .…”

Unconventional interlayer exchange coupling via chiral phonons in synthetic magnetic oxide heterostructures

“…Note that the out-ofplane M (T) shows the conventional FM behaviors of SRO with the same T c and without any downturn, consistent with previous studies (fig. S5) (21,(24)(25)(26)(27). Magnetic field (H)-dependent in-plane magnetization [M (H)] curves of the superlattices consistently support the AFM-like behavior, with a double hysteresis loop and a large coercive field of ~1.8 T appearing below ~80 K (Fig.…”

“…We deliberately grew oxide superlattices with alternating and -atomic unit cells (~0.4 nm) of SRO (t SRO ) and STO (t STO ), respectively, repeated for  times on STO (001) substrates, i.e., [|]  , using pulsed laser epitaxy (see Materials and Methods and figs. S1 to S3) (21,(24)(25)(26)(27). An intriguing oscillation in the in-plane magnetization is observed as a function of t STO , indicating the presence of an unconventional IEC across the NM-I spacer.…”

Observation of metallic electronic structure in a single-atomic-layer oxide

“…Based on this analogy, we chose a single-atomic-layerthick SRO film (Fig. 1a) whose electronic ground state is currently under debate [27,28]. The monolayer SRO can be also regarded as a two-dimensional analogue of a metallic single layer perovskite Sr 2 RuO 4 which has been intensively studied for its unconventional superconductivity [29] and recently for magnetism [30].…”