Unusual Magneto thermal Transport Properties of 3D Dirac Semimetal Cd3As2

Thermoelectric power of Dirac semimetal Cd3As2 exhibits linear temperature dependence, which is in agreement with the semiclassical Mott’s relation. Linear energy dispersion of three-dimensional Dirac fermion is clearly reflected in high field saturation of thermoelectric power. The scattering time crosses over from nearly energy independent to linear energy dependent with increasing magnetic field. Unlike electrical resistivity, the electronic part of thermal conductivity decreases rapidly and it completely suppresses within a few tesla of magnetic fields. As a result, we have observed a remarkable violation of Wiedemann-Franz law (WFL) under application of magmatic field in Cd3As2 and the violation becomes more and more drastic with increasing magnetic field strength.  This implies that the fundamental concept of Landau quasiparticle no longer holds in Cd3As2 in presence of magnetic field. Our constructed schematic diagram based on experimental findings introduces a special point, which looks like magnetic field induced quantum critical point (QCP) as observed in heavy
fermion compounds YbRh2Si2, Sr3Ru2O7, etc.

(Ref. (1) arXiv: 1502.02264; (2) arXiv: 1508.02286)