Charge‐Transfer‐Induced Multivalent States with Resultant Emergent Magnetism in Transition‐Metal Oxide Heterostructures

Abstract

Transition‐metal oxide (TMO) heterostructures provide fertile grounds for creating and manipulating intriguing properties and functionalities. At the interface of TMO heterostructures, electronic reconstructions generally occur via charge transfer and lead to an extraordinary spectrum of emergent phenomena but unattainable in their bulk constituents. However, the basic mechanism of charge transfer at the interface is not fully determined or even understood in heterostructures, which may hide the underlying mechanisms and intriguing physics. Herein, an intrinsic charge transfer and resultant exotic ferromagnetism are unambiguously observed in the heterostructures between the nonmagnetic LaCoO3 (LCO) and SrTiO3 (STO). Combining element‐specific X‐ray absorption spectroscopy and atomic multiplet fitting, direct evidence of charge transfer‐induced multivalence of cobalt ions, interactions of which would contribute to the novel magnetism beyond the intuition, in concert with first‐principles density‐functional‐theory calculations, is demonstrated. Beyond LCO/STO system, a more broadly applicable principle for the heterostructures between 3d TMO and STO where charge transfer and resultant multivalence or conducting interfaces are coexistent is establish. This study represents an advance that the electronic reconstruction and the multiple electron configurations of 3d transition metal ions will constitute a powerful tool for the designs of functional materials and creations of unconventional physical properties.

Unraveling the Correlation between the Interface Structures and Tunable Magnetic Properties of La1–xSrxCoO3−δ/La1–xSrxMnO3−δ Bilayers Using Deep Learning Models

“…In the La 0.7 Sr 0.3 CoO 3−δ /La 0.7 Sr 0.3 MnO 3−δ model, the higher concentration of oxygen vacancies in the LSCO layers may result in more significant structural distortion and rotation in the CoO x octahedral polyhedra compared to the MnO x octahedra in the LSMO layers (a detailed examination of the structural changes in the Co/MnO x polyhedra is presented in the following paragraphs). Since Co and Mn ions have multiple valence and magnetization states, this heterogeneous distribution of oxygen vacancies and the accompanying structural distortion of Co/MnO x polyhedra also affect the valence charge of the transition metal (TM) ions.…”

First-principles design of ferromagnetic monolayer MnO2 at the complex interface

“…One of the most representative instances is the transition metal complex oxide LaAlO 3 / SrTiO 3 interface confining quasi twodimensional electron gas (2DEG) at the nanoscale [30,31]. Control variables have been successfully utilized to manipulate the 2DEG, such as fully optical modulation [32], electronic reconstructions [33], ferroelectric polarization [34], electric field-effect through the gate [35]. Surprisingly, the fascinating interface even also supports superconductivity [36], electronic phase separation [37,38], and strong Rashba spin-orbital coupling [39].…”

Boron-induced oxygen vacancies for methanol oxidation reaction: selectivity towards formate via non-noble metals

“…17,18 Among various TMOs, spinel nickel–cobalt oxide has gained significant interest because of partially filled d-valence orbitals, which induce spin and orbital degrees of freedom, resulting in better electrochemical activity. 19,20…”