Thursday, January 10, 2013

1301.1743 (Xiao-Qing Yan et al.)

Experimental observation of polarization-dependent ultrafast carrier
dynamics in multi-layer graphene
   [PDF]

Xiao-Qing Yan, Zhi-Bo Liu, Jun Yao, Xin Zhao, Xu-Dong Chen, Fei Xing, Yongsheng Chen, Jian-Guo Tian
Polarization characteristic of ultrafast carrier dynamics in multi-layer graphene is probed with a tilted beam (with respected to the graphene plane). The transient reflectivity signal \DeltaR/R depends greatly on polarizations (i.e., orientation of linear polarization) of both pump and probe beams. The \DeltaR/R signal at long delay times (~1 ps), which has been reported to associate with the carrier-phonon scattering or electron-hole recombination process, could be continuously altered from positive to negative by changing the polarization of probe beam from P to S when the dynamics is probed by a total internal reflection beam. And the \DeltaR/R signal at 0 delay time, which is negative in literature, is positive and could be altered to negative by changing the polarization of probe beam when the probe beam is non-total internal reflection beam. These extremely unexpected experiment results prompt the carrier relaxation of graphene should be further studied although there are lots of reports on the ultrafast carrier dynamics of graphene and graphite. Using beams with different wavelength and tilted angle to probe the carrier relaxation may offer a way to map the carrier relaxation process and to study the interaction between hot carriers and electron spin in graphene.
View original: http://arxiv.org/abs/1301.1743

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