Peng Xu, Guo Yuqiao, Yin Qin, Wu Junchi, Zhao Jiyin, Wang Chengming, Tao Shi, Chu Wangsheng, Wu Changzheng, Xie Yi
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.
National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, P. R. China.
J Am Chem Soc. 2017 Apr 12;139(14):5242-5248. doi: 10.1021/jacs.7b01903. Epub 2017 Mar 29.
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 MnO nanosheet 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 MnO nanomaterials 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 MnO nanosheet 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.
电子态跃迁，尤其是金属-绝缘体跃迁（MIT），具有一些在引人关注的能源应用和智能设备中有用的物理特性。但迄今为止，很少有简单的金属氧化物被证明在室温附近会发生电子态跃迁。在此，我们通过实验证明，二维（2D）纳米材料中双交换的化学诱导会在室温附近引发金属-绝缘体跃迁。在这种情况下，二维MnO纳米片的价态调控诱导出具有双交换效应的Mn(III)-O-Mn(IV)结构，成功触发了具有超高负磁阻（MR）的近室温电子跃迁。二维MnO纳米材料中的双交换在287 K时表现出高达-11.3%（0.1 T）的超高磁阻值，这是二维纳米材料中接近室温时报道的最高负磁阻值。此外，MnO纳米片在从270 K到290 K变化时显示出7.1%的红外透过率变化。我们预计，双交换结构的维度限制有望为智能设备带来新颖的磁输运特性和灵敏响应。
