Mixed-State Quasiparticle Transport in High-TcCuprates

Theory of quasiparticle transport in the mixed state of a $d$-wave superconductor is developed under the assumption of disordered vortex array. A novel universal regime is identified at fields above $H^{*}{=c}^{*}{H}_{c2\mathrm{}}(T/T_c{)}^2$, characterized by a field-independent longitudinal thermal conductivity ${\kappa }_{\mathrm{xx}}^e$. It is argued that this behavior is responsible for the high-field plateau in ${\kappa }_{\mathrm{xx}}^e$ experimentally observed in high- $T_c$ cuprates.