Transport, optical and electronic properties of the half metal CrO2

The half metal ferromagnet CrO2 has interesting and unusual electronic prop erties. As in many other cases when kinetic properties are not easily descr ibed by the conventional Bloch-Boltzmann theory, strong correlation effects of the Hubbard type were called for explanation of the electronic properti es of CrO2. Here we report detailed analysis of the electronic structure an d related properties of CrO2, based on state-of-the-art density functional calculations. We conclude that (1) the most current experimental data do no t indicate an anomalously large mass renormalization, (2) temperature depen dence of the resistivity is due mainly to the scattering by spin fluctuatio ns, (3) coupling between charge (electrons) and spin (magnons) degrees of f reedom is anomalously strong, (4) recent optical measurements can be reason ably interpreted within the quasi-one-electron density functional calculati ons, and (5) their deviation from the experiment is opposite to that expect ed in the Hubbard model, and agrees with a physical picture of electrons dr essed by spin fluctuations. (C) 1999 The American Physical Society. [S0556- 2821(99)03904-1].