Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA.
Science. 2010 Feb 5;327(5966):665-9. doi: 10.1126/science.1183640.
Electronic states in disordered conductors on the verge of localization are predicted to exhibit critical spatial characteristics indicative of the proximity to a metal-insulator phase transition. We used scanning tunneling microscopy to visualize electronic states in Ga(1-x)Mn(x)As samples close to this transition. Our measurements show that doping-induced disorder produces strong spatial variations in the local tunneling conductance across a wide range of energies. Near the Fermi energy, where spectroscopic signatures of electron-electron interaction are the most prominent, the electronic states exhibit a diverging spatial correlation length. Power-law decay of the spatial correlations is accompanied by log-normal distributions of the local density of states and multifractal spatial characteristics.
在接近局域化的无序导体中的电子态预计会表现出临界的空间特征，表明其接近金属-绝缘体相变。我们使用扫描隧道显微镜来可视化接近这个相变的 Ga(1-x)Mn(x)As 样品中的电子态。我们的测量结果表明，掺杂诱导的无序在很宽的能量范围内产生了局域隧道电导的强烈空间变化。在费米能级附近，电子-电子相互作用的光谱特征最为突出，电子态表现出发散的空间相关长度。空间相关性的幂律衰减伴随着局域态密度的对数正态分布和多重分形的空间特征。
