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Persistent Surface Metal-Insulator Transition on a Nonstoichiometric Manganite Film

Persistent Surface Metal-Insulator Transition on a Nonstoichiometric Manganite Film. CNMS User Project Highlight. Scientific Achievement

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Persistent Surface Metal-Insulator Transition on a Nonstoichiometric Manganite Film

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  1. Persistent Surface Metal-Insulator Transition on a Nonstoichiometric Manganite Film CNMS User Project Highlight Scientific Achievement Although oxygen-deficient manganite thin films are insulating, the surface of these films exhibits a metal-insulator transition (MIT) at 120 K, coincident with the onset of ferromagnetic ordering of small clusters in the bulk of the oxygen-deficient film. Significance and Impact The surprising proximity of the surface MIT temperature of nonstoichiometric films with that of the fully oxygenated bulk suggests that the electronic properties in the surface region are not significantly affected by oxygen deficiency in the bulk. This carries important implications for the understanding and functional design of complex oxides and their interfaces with specific electronic properties for catalysis, oxide electronics and electrochemistry. Research Details • In situtemperature-dependent scanning tunnelling spectroscopy experiments were performed on pristine oxygen deficient, epitaxial LPCMO films that have not been exposed to ambient conditions. • Zero-bias conductance in the tunnelling spectra shows a MIT at 120K, which is explained by comparing with ex situ in-plane electronic transport and magnetic properties. Current (nA) Temperature(K) Voltage(V) Temperature dependent electronic and magnetic properties of the oxide surface. Work was performed in the Materials Science and Technology Division and at CNMS – ORNL. • Paul C. Snijders, Min Gao, Hangwen Guo, Guixin Cao, Wolter Siemons, Hongjun Gao, Thomas Z. Ward, Jian Shen, and Zheng Gai, Nanoscale, 2013. DOI: 10.1039/C3NR02343E.

  2. Insulating to metallic transition at the surface of a manganite film CNMS User Project Highlight Scientific Achievement Scanning probe studies at the surface of manganite films show that the electronic properties of the surface of the film with reduced oxygen content are similar to that of fully oxygenated material, that is, it exhibits a transition from insulating to metallic. Significance and Impact The electronic properties of the manganite films are not significantly affected whether or not oxygen vacancies are formed. This carries important implications for the understanding and functional design of complex oxides and their interfaces with specific electronic properties for catalysis, oxide electronics and electrochemistry. Research Details In situ temperature dependent scanning probe spectroscopy experiments were performed on pristine oxygen deficient, manganite films that have not been exposed to ambient conditions. Current (nA) Temperature dependent electronic properties of the oxide surface as measured using scanning probe spectroscopy. Temperature(K) Voltage(V) • Paul C. Snijders, Min Gao, Hangwen Guo, Guixin Cao, Wolter Siemons, Hongjun Gao, Thomas Z. Ward, Jian Shen, and Zheng Gai, Nanoscale,2013. DOI: 10.1039/C3NR02343E. Work was performed in the Materials Science and Technology Division and at CNMS – ORNL.

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