NMR in magnetically ordered solids

The peculiar features of NMR studies in solids with ordered atomic spin systems are outlined briefly. Because of the rather large magnetic hyperfine fields (10² to 10⁴ kG) the NMR frequencies (10² to 10⁴ MHz) can be located only by means of frequency variable spectrometers. Two successful radio frequency techniques are discussed briefly: a continuous-wave bridge-type spectrometer for frequencies between 10 and 1000 MHz, and a phase-coherent pulsed NMR spectrometer tunable between 16 and 200 MHz. Recent advances in the measurement and analysis of NMR frequencies, rf enhancement factors, and spin-spin relaxations of nuclei within ferromagnetic domains and walls are discussed for some typical studies using polycrystalline and single crystal samples of the systems, ⁶¹Ni in Ni metal, ⁵³Cr in hcp and fcc Co metal, ¹⁵¹Eu and ¹⁵³Eu in EuO, EuS and EuSe. (author)