Fig. 3
From: Evidence for the weakly coupled electron mechanism in an Anderson-Blount polar metal
Microscopic origin of the two relaxations in LiOsO3. a–d Fluence dependence of the transient reflectivity of LiOsO3 at T = 80 K as captured by the parameters of the bi-exponential model. Both the amplitudes of a fast and b slow relaxation processes display a linear dependence that is characteristic of the linear response regime. However, the decay constants of a fast and b slow relaxation processes display a lack of fluence dependence that is indicative of intra-band photo-carrier relaxation and therefore suggests a selective electron–phonon coupling in LiOsO3. Black lines in a–d are linear fits of the data while error bars derive from the χ2 of the bi-exponential fits. e Schematic of microscopic origin of the relaxation processes of LiOsO3. Electrons, initially excited to a high effective temperature Te by the pump pulse, relax on the time scale τf by thermalizing with only a set of strongly coupled phonons (SCPs) at temperature Ts via electron–phonon coupling gep. The SCPs then relax on a time scale τs by thermalizing with the rest of the lattice modes, referred to as the weakly coupled phonons (WCPs) at temperature Tw, via phonon–phonon coupling gpp. The relative heat capacities of the two phononic thermal baths are found by partitioning the total lattice heat capacity Cp by the parameter α
