title: Unusual ferromagnetism enhancement in ferromagnetically optimal manganite La0.7-yCa0.3+yMn1-yRuyO3 (0≤y<0.3): the role of Mn-Ru t2g super-exchange.
abstract: The eg-orbital double-exchange mechanism as the core of physics of colossal magnetoresistance (CMR) manganites is well known, which usually covers up the role of super-exchange at the t2g-orbitals. The role of the double-exchange mechanism is maximized in La0.7Ca0.3MnO3, leading to the concurrent metal-insulator transition and ferromagnetic transition as well as CMR effect. In this work, by a set of synchronous Ru-substitution and Ca-substitution experiments on La0.7-yCa0.3+yMn1-yRuyO3, we demonstrate that the optimal ferromagnetism in La0.7Ca0.3MnO3 can be further enhanced. It is also found that the metal-insulator transition and magnetic transition can be separately modulated. By well-designed experimental schemes with which the Mn(3+)-Mn(4+) double-exchange is damaged as weakly as possible, it is revealed that this ferromagnetism enhancement is attributed to the Mn-Ru t2g ferromagnetic super-exchange. The present work allows a platform on which the electro-transport and magnetism of rare-earth manganites can be controlled by means of the t2g-orbital physics of strongly correlated transition metal oxides.
authors.affiliation: Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: M F
authors.initials: MF
authors.lastname: Liu
authors.affiliation: Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Z Z
authors.initials: ZZ
authors.lastname: Du
authors.affiliation: Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Y L
authors.initials: YL
authors.lastname: Xie
authors.affiliation: Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.affiliation: Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Z B
authors.initials: ZB
authors.lastname: Yan
authors.affiliation: 1] Laboratory of Solid State Microstructures and Innovative Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China [2] Institute for Advanced Materials and Laboratory of Quantum Engineering and Materials, South China Normal University, Guangzhou 510006, China.
authors.forename: J-M
authors.initials: JM
authors.lastname: Liu