Nuclear Magnetic Resonance in NiF2 Domain Walls

Abstract

Two additional nuclear resonances of the ${\mathrm{F}}^{19}$ nuclei are observed in the antiferromagnetic state of ${\mathrm{NiF}}_2$ . These resonances can be observed in zero magnetic field at $\text{ν\hspace{0.17em}=\hspace{0.17em}26.6\hspace{0.17em}}\mathrm{Mc}/\sec$ and $\text{ν\hspace{0.17em}=\hspace{0.17em}−51.2\hspace{0.17em}}\mathrm{Mc}/\sec$ . They are broad, asymmetric, and easily saturated, with an apparent value of $T_1\text{∼8\hspace{0.17em}}\sec$ , at 20.30°K. They correspond to internal fields along [110] and [1̄1̄0] directions respectively for $H_0$ along [110]. These compare quite well with the theoretical values of +18.7 Mc/sec and −54.4 Mc/sec calculated from the measured interaction parameters for a spin alignment along [110] and [1̄1̄0]. These two resonances arise from ${\mathrm{F}}^{19}$ nuclei in the domain walls.