Nuclear quadrupole interaction and zero first-order Zeeman transitions of ${}^{167}$Er${}^{3+}$ in CaWO${}_4$

Lewin Marsh, Yikai Yang, Cesare Mattiroli +5

We report microwave spectroscopy of ${}^{167}$Er${}^{3+}$ doped in CaWO${}_4$ which reveals the hyperfine splitting of the erbium electronic ground state ($Z_1$, $J_{eff.}$=15/2)…