Qazilbash M M, Brehm M, Chae Byung-Gyu, Ho P-C, Andreev G O, Kim Bong-Jun, Yun Sun Jin, Balatsky A V, Maple M B, Keilmann F, Kim Hyun-Tak, Basov D N
Physics Department, University of California-San Diego, La Jolla, CA 92093, USA.
Science. 2007 Dec 14;318(5857):1750-3. doi: 10.1126/science.1150124.
Electrons in correlated insulators are prevented from conducting by Coulomb repulsion between them. When an insulator-to-metal transition is induced in a correlated insulator by doping or heating, the resulting conducting state can be radically different from that characterized by free electrons in conventional metals. We report on the electronic properties of a prototypical correlated insulator vanadium dioxide in which the metallic state can be induced by increasing temperature. Scanning near-field infrared microscopy allows us to directly image nanoscale metallic puddles that appear at the onset of the insulator-to-metal transition. In combination with far-field infrared spectroscopy, the data reveal the Mott transition with divergent quasi-particle mass in the metallic puddles. The experimental approach used sets the stage for investigations of charge dynamics on the nanoscale in other inhomogeneous correlated electron systems.
关联绝缘体中的电子由于它们之间的库仑排斥作用而无法导电。当通过掺杂或加热在关联绝缘体中诱导出绝缘体到金属的转变时，所产生的导电状态可能与传统金属中自由电子所表征的状态截然不同。我们报道了一种典型的关联绝缘体二氧化钒的电子特性，其中金属态可通过升高温度来诱导。扫描近场红外显微镜使我们能够直接成像在绝缘体到金属转变开始时出现的纳米级金属小区域。结合远场红外光谱，这些数据揭示了金属小区域中准粒子质量发散的莫特转变。所采用的实验方法为研究其他非均匀关联电子系统中纳米尺度上的电荷动力学奠定了基础。
