Addendum to "Hyperfine interaction in the lowest levels of theH43andD21states of trivalent praseodymium in yttrium aluminum perovskite (Y AIO3)"

The magnetic hyperfine tensor of ${\mathrm{Pr}}^{3+}$ in single-crystal Y Al${\mathrm{O}}_3$ has been measured in the ground electronic state through a study of the $I_z=\frac{1}{2}-I_z=\frac{3}{2}$ NMR transitions in a low static magnetic field. The directions of the $x$, $y$, and $z$ axes of the two ${\mathrm{Pr}}^{3+}$ sites are determined. The magnetic splitting factors are ${\gamma }_z=11.648\mathrm{}\pm 0.053$, ${\gamma }_x=3.881\mathrm{}\pm 0.036$, and ${\gamma }_y=2.50\mathrm{}\pm 0.1$ kHz/G. The pseudoquadrupole interaction from the second-order magnetic hyperfine interaction is found to account for 94% of the observed zero-field splittings.