Mott-Hubbard gaps and their doping-induced collapse in strongly correlated pyrochlore ruthenates
Mott-Hubbard gaps and their doping-induced collapse in strongly correlated pyrochlore ruthenates
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强相关烧绿石钌酸盐中的莫特-哈伯德能隙及其掺杂引起的塌陷
DOI：
10.1103/physrevb.102.041114
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发表时间：
2020
影响因子：
3.7
通讯作者：
Tokura Y.
中科院分区：
文献类型：
--
作者：
Kaneko R.;Ueda K.;Terakura C.;Tokura Y.
我们研究了烧绿石（稀土离子）填充控制金属-绝缘体转变（MIT）过程中电荷动力学的变化。随着离子从 Lu 到 Pr 的广泛变化，反铁磁转变温度系统地升高，而在假设的带宽控制莫特转变中，电荷间隙的大小减小到零。这是由于莫特-哈伯德绝缘体体系中有效电子相关性的降低。掺杂空穴产生了从反铁磁绝缘体到顺磁金属的填充控制 MIT，并伴随着莫特-哈伯德能隙的塌陷。掺杂引起的光导率从带隙上方区域到带隙内区域的光谱权重转移几乎与掺杂水平成正比，其速率随着电子相关性的降低而增强，符合标准莫特临界性。
We investigate the variation of charge dynamics in the course of the filling-control metal-insulator transitions (MITs) for pyrochlore(being rare-earth ions). With widely changing ofions from Lu to Pr, the antiferromagnetic transition temperature systematically increases while the magnitude of the charge gap decreases toward zero at the hypothetical bandwidth-control Mott transition. It is attributable to the reduction of effective electron correlation in the Mott-Hubbard insulator regime. Doping holes give rise to the filling-control MITs from antiferromagnetic insulators to paramagnetic metals accompanied by the collapse of the Mott-Hubbard gaps. The doping-induced spectral weight transfer of the optical conductivity from the above-gap region to the in-gap region is nearly proportional to the doping level, whose rate is enhanced with the reduction of the electron correlation, in accord with the standard Mott criticality.