飞秒泵浦探针光谱学研究莫特绝缘体 UO₂ 中 5f 电子的超快跃迁动力学。

Ultrafast hopping dynamics of 5f electrons in the Mott insulator UO₂ studied by femtosecond pump-probe spectroscopy.

机构信息

Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

出版信息

Phys Rev Lett. 2011 May 20;106(20):207402. doi: 10.1103/PhysRevLett.106.207402.

DOI:10.1103/PhysRevLett.106.207402

Abstract

We describe a femtosecond pump-probe study of ultrafast hopping dynamics of 5f electrons in the Mott insulator UO₂ following Mott-gap excitation at temperatures of 5-300 K. Hopping-induced response of the lattice and electrons is probed by transient reflectivity at mid- and above-gap photon energies, respectively. These measurements show an instantaneous hop, subsequent picosecond lattice deformation, followed by acoustic phonon emission and microsecond relaxation. Temperature-dependent studies indicate that the slow relaxation results from Hubbard excitons formed by U³⁺-U⁵⁺ pairs.

摘要

我们描述了飞秒泵浦探测研究超快跳变动力学在 5f 电子在莫特绝缘体 UO₂在莫特能隙激发温度 5-300 K。跳变诱导晶格和电子的响应分别由中能隙和高能隙光子的瞬态反射率探测。这些测量显示出瞬时跳变，随后是皮秒晶格变形，接着是声子发射和微秒弛豫。温度依赖的研究表明，慢弛豫是由 U³⁺-U⁵⁺对形成的 Hubbard 激子引起的。