Temperature dependence of the hyperfine magnetic field in SrRuO₃ measured by the ⁹⁹Ru Mössbauer effect

The hyperfine magnetic field in the ferromagnetic metal, SrRuO₃, has been measured from 4.2 to 166.3 K by the ⁹⁹Ru Mossbauer effect. The hyperfine field at 4.2 K is determined to be 33.0(0.4) T with an isomer shift of -0.33(.02) mm/s. The Curie temperature is determined 162(2) K for a polycrystalline sample. This is consistent with the determination by Cao et al. [Phys. Rev. B 56, 321 (1997)] of T_C=165K for a single crystal. The Mossbauer effect full width at half maximum linewidth at 166.3(0.1) K, above the Curie temperature, is as narrow as the natural linewidth of Mossbauer effect state without broadening due to regions of short range ferromagnetic order. This indicates that the compound at this temperature is in a paramagnetic state.