1098-0121
Ultrafast photodoping and effective Fermi-Dirac distribution of the Dirac particles in Bi2Se3
Crepaldi
A.
Ecole Polytech Fed Lausanne, ICMP, CH-1015 Lausanne, Switzerland
Ressel
B.
Elettra Sincrotrone Trieste, Trieste, Italy
Cilento
F.
Elettra Sincrotrone Trieste, Trieste, Italy
Zacchigna
M.
CNR IOM, Trieste, Italy
Grazioli
C.
Elettra Sincrotrone Trieste, Trieste, Italy
Berger
H.
Ecole Polytech Fed Lausanne, ICMP, CH-1015 Lausanne, Switzerland
Bugnon
Ph.
Ecole Polytech Fed Lausanne, ICMP, CH-1015 Lausanne, Switzerland
Kern
K.
Ecole Polytech Fed Lausanne, ICMP, CH-1015 Lausanne, Switzerland
Grioni
M.
Ecole Polytech Fed Lausanne, ICMP, CH-1015 Lausanne, Switzerland
Parmigiani
F.
Elettra Sincrotrone Trieste, Trieste, Italy
2012
We exploit time- and angle-resolved photoemission spectroscopy to determine the evolution of the out-of-equilibrium electronic structure of the topological insulator Bi2Se3. The response of the Fermi-Dirac distribution to ultrashort IR laser pulses has been studied by modeling the dynamics of hot electrons after optical excitation. We disentangle a large increase in the effective temperature (T*) from a shift of the chemical potential (mu*), which is consequence of the ultrafast photodoping of the conduction band. The relaxation dynamics of T* and mu* are k independent and these two quantities uniquely define the evolution of the excited charge population. We observe that the energy dependence of the nonequilibrium charge population is solely determined by the analytical form of the effective Fermi-Dirac distribution.
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