The Origin of Oxygen Vacancies Controlling La_2/3Sr_1/3MnO₃ Electronic and Magnetic Properties

Mixed-valence manganites gain increasing attentions thanks to their extraordinary properties including half-metallicity and colossal magnetoresistive response, rendering them ideal candidate for oxide spintronics applications. Oxygen vacancies in oxides have been approved to be important functional defects and are effective to manipulating their multifunctional properties. To gain a deep insight into the roles of oxygen vacancies on regulating the atomic structure and electronic properties of the mixed-valence manganites, two high-quality epitaxial La_2/3Sr_1/3MnO₃ films around a critical point (without/with oxygen vacancies) were designed and fabricated. From the experiments and theoretical calculations, it was found that the oxygen vacancies induce a weakening of Mn-O-Mn hybridized bond and an increase of concentration of Mn³⁺ ions, impair the double exchange between Mn³⁺ and Mn⁴⁺, and therefore lead to the transition from metal to insulator and the degraded magnetic properties. Our finding demonstrates a practical approach to tune the magnetic and transport properties of oxide thin films by precisely controlling the oxygen vacancies for high performance spintronics applications.