Oral
13 Jan 2025
Unveiling the interplay between changes in the concentration of mobile defects (such as oxygen vacancies) and functional properties in relevant materials represents a step forward in both fundamental research and potential applications. In this work, we focus on thin films of mixed ionic-electronic conductor La0.5Sr0.5FeO3-δ (LSF50), a perovskite oxide which has shown interesting optical, electric and magnetic properties in previous studies, and finds application in solid oxide fuel cell electrodes, as a catalyst in oxygen evolution reactions, or as a functional material in computing devices.[1,2,3] However, precise and continuous control of the oxygen stoichiometry, a reversible way of tuning the vacancy content after the synthesis of the film, has yet not been fully studied. For this reason, the oxygen content of a LSF50 film was controlled by means of low voltage modulation (<1 V). Its functional properties were tailored as function of the oxygen content, revealing a strong correlation between electrical conductivity an magnetic order transition in the material. To display the potential of the LSF50, a gold rail-like design was patterned on top of a LSF50 film (see figure). This configuration allowed for a high throughput range of oxidation states within the same film after voltage treatment. Subsequently, a ferromagnetic (FM) 2.5-nm Co layer was deposited on top, and coupled through a field cooling (FC) from 325 K. The TN was expected to progressively decrease along the rails, which was confirmed by a gradual decrease in the Co coercivity (HC) after the point where TN was meant to be close to RT. The HC of the FM, which depended on the oxidation state of the AFM LSF50 buried underneath, could be used as a reference to assess the electric and optical properties of the LSF50, therefore providing a contactless way of reading the information stored in the LSF50, which ultimately can be utilized to read information from spintronic and neuromorphic devices.References: [1] S. P. Simner, et al., Electrochem. Solid St., 5 (2002), DOI: 10.1149/1.1483156 [2] Z. Shen, et al., J. Mater. Chem. A, 8 (2020), DOI: 10.1039/C9TA13313E [3] A. Krick, et al., APL Mater., 5 (2017), DOI: 10.1063/1.4982249
