Superhyperfine structure of the EPR spectra of impurity ions in the LiYF$_4$:Nd$^{3+}$ system doped by $^{143}$Nd isotopes

Results of measuring the EPR spectra in the LiYF$_4$:Nd$^{3+}$ system doped by $^{143}$Nd isotopes with the nuclear spin $I$ = 7/2 have been presented. We have succeeded to observe superhyperfine splitting of the EPR spectra of the samples under investigation at the orientation of the magnetic field $\mathbf{B}$ along the symmetry axis $c$ of the crystal and at $\mathbf{B}\perp\mathbf{c}$ on the lines corresponding to both even neodymium isotopes and $^{143}$Nd.