title: Dynamical Evolution of Anisotropic Response in Black Phosphorus under Ultrafast Photoexcitation.
abstract: Black phosphorus has recently emerged as a promising material for high-performance electronic and optoelectronic device for its high mobility, tunable mid-infrared bandgap, and anisotropic electronic properties. Dynamical evolution of photoexcited carriers and the induced transient change of electronic properties are critical for materials' high-field performance but remain to be explored for black phosphorus. In this work, we perform angle-resolved transient reflection spectroscopy to study the dynamical evolution of anisotropic properties of black phosphorus under photoexcitation. We find that the anisotropy of reflectivity is enhanced in the pump-induced quasi-equilibrium state, suggesting an extraordinary enhancement of the anisotropy in dynamical conductivity in hot carrier dominated regime. These results raise attractive possibilities of creating high-field, angle-sensitive electronic, optoelectronic, and remote sensing devices exploiting the dynamical electronic anisotropy with black phosphorus.
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Shaofeng
authors.initials: S
authors.lastname: Ge
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Chaokai
authors.initials: C
authors.lastname: Li
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Chenglong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Yudao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Qiu
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Qinsheng
authors.initials: Q
authors.lastname: Wang
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|§Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, People's Republic of China.
authors.forename: Junku
authors.initials: J
authors.lastname: Liu
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Jia
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Ji
authors.initials: J
authors.lastname: Feng
authors.affiliation: †International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China.|‡Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Dong
authors.initials: D
authors.lastname: Sun
keywords: Black phosphorus; electronic anisotropy; high field transport; hot carriers; two-dimensional materials; ultrafast spectroscopy