Transport properties in the d-density-wave state in an external magnetic field:: The Wiedemann-Franz law -: art. no. 144509

We derive the electrical and thermal conductivities of the d-density-wave state in an external magnetic field B in the low-temperature regime and in the presence of impurities. We show that in the zero-temperature limit, T-->0, the Wiedemann-Franz (WF) law remains intact irrespectively of the value of the applied field and chemical potential mu as soon as there is scattering from impurities. For finite T less than or similar to /mu/ to the WF law violation is possible and it is enhanced by the external field. Depending on the relative values of B and T the electrical conduction may dominate the heat conduction and vice versa. For mu>>T the WF is restored even in the presence of the external field.