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Regular version of the site

Article

Quasiparticle and Nonquasiparticle Transport in Doped Quantum Paraelectrics

Physical Review Letters. 2021. Vol. 126.
Kumar A., Yudson Vladimir I., Maslov D. L.

Charge transport in doped quantum paraelectrics (QPs) presents a number of puzzles, including a
pronounced T^2 regime in the resistivity. We analyze charge transport in a QP within a model of electrons
coupled to a soft transverse optical (TO) mode via a two-phonon mechanism. For T above the soft-mode
frequency but below some characteristic scale (E_0), the resistivity scales with the occupation number of
phonons squared, i.e., as T^2. The T^2 scattering rate does not depend on the carrier number density and is not
affected by a crossover between degenerate and nondegenerate regimes, in agreement with the experiment.
Temperatures higher than E_0 correspond to a nonquasiparticle regime, which we analyze by mapping the
Dyson equation onto a problem of supersymmetric quantum mechanics. The combination of scattering by
two TO phonons and by a longitudinal optical mode explains the data quite well.