title: Double-Exchange Effect in Two-Dimensional MnO2Nanomaterials.
abstract: Electronic state transitions, especially metal-insulator transitions (MIT), offer physical properties that are useful in intriguing energy applications and smart devices. But to-date, very few simple metal oxides have been shown to undergo electronic state transitions near room temperature. Herein, we demonstrate experimentally that chemical induction of double-exchange in two-dimensional (2D) nanomaterials brings about a MIT near room temperature. In this case, valence-state regulation of a 2D MnO2nanosheet induces a Mn(III)-O-Mn(IV) structure with the double-exchange effect, successfully triggering a near-room-temperature electronic transition with an ultrahigh negative magneto-resistance (MR). Double-exchange in 2D MnO2nanomaterials exhibits an ultrahigh MR value of up to -11.3% (0.1 T) at 287 K, representing the highest reported negative MR values in 2D nanomaterials approaching room temperature. Also, the MnO2nanosheet displays an infrared response of 7.1% transmittance change on going from 270 to 290 K. We anticipate that dimensional confinement of double-exchange structure promises novel magneto-transport properties and sensitive responses for smart devices.
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China.
authors.forename: Xu
authors.initials: X
authors.lastname: Peng
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China.
authors.forename: Yuqiao
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Yin
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China.
authors.forename: Junchi
authors.initials: J
authors.lastname: Wu
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China.
authors.forename: Jiyin
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China.
authors.forename: Chengming
authors.initials: C
authors.lastname: Wang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, P. R. China.
authors.forename: Shi
authors.initials: S
authors.lastname: Tao
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, P. R. China.
authors.forename: Wangsheng
authors.initials: W
authors.lastname: Chu
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China.
authors.forename: Changzheng
authors.identifier: http://orcid.org/0000-0002-4416-6358
authors.initials: C
authors.lastname: Wu
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China.
authors.forename: Yi
authors.identifier: http://orcid.org/0000-0002-1416-5557
authors.initials: Y
authors.lastname: Xie