Unifying explanation for carrier relaxation anomaly in gapped systems
arXiv:1202.2635
Abstract
We develop a theory to describe energy relaxation of photo-excited carriers in low-temperature ordered states with band gap opening and formulate carrier relaxation time $Ï$ near and below transition temperature $T_{\mathrm{c}}$ by quantifying contributions from different carrier-phonon scatterings to the relaxation rate. The theory explains anomalous experimental observations of $Ï$ in gapped systems. Transverse acoustic (TA) phonon modes play a crucial role in carrier relaxation; their heat capacity determines $Ï$-divergence near $T_{\mathrm{c}}$. The theory is validated by fitting $Ï$ of fullerene polymers onto a theoretical curve.
5 pages, 3 figures