Electronic structure of ${\mathrm{CrO}}_2$ as deduced from its magneto-optical Kerr spectra

We report a combined experimental-computational investigation of the electronic structure of ${\mathrm{CrO}}_2.$ We have measured the magneto-optical Kerr spectra of ${\mathrm{CrO}}_2$ at 10 K and 300 K. At 10 K the Kerr signal is significantly enhanced over that obtained at 300 K. We compare the measured Kerr spectra to first-principles theoretical spectra, which we computed using three different approximations to the exchange-correlation functional, i.e., the local spin-density approximation (LSDA), generalized gradient approximation (GGA), and $\mathrm{LSDA}+U.\mathrm{}$ The experimental low-temperature magneto-optical Kerr spectra are best explained by calculations employing the GGA functional. The addition of an on-site Coulomb correlation U does not lead to reasonable Kerr spectra.