Effects of low magnetic fields in transient spectral hole-burning of the R1-line in emerald, Be3Al2Si6O18:Cr(III)

Polarized transient spectral hole-burning in the R1-line (2Ā(2E) ← 4A2) of Chatham lab grown emerald is reported as a function of low magnetic fields B∥c and B⊥c (<16 mT) and temperature. The experiments yield g-factors g⊥(4A2)=1.96 ± 0.02, g∥(4A2)=1.97 ± 0.02 and g∥[2Ā(2E)]=1.02 ± 0.03. The hole patterns indicate that spin-lattice relaxation between the Zeeman split spin levels of the ground and excited state is slow at 2.5 K. Spin-lattice relaxation by an Orbach process appears to become efficient for the 2Ā(2E) levels at temperatures >8 K on the 2.5 ms experimental timescale but thermalization between the ±3/2 4A2 levels stays relatively slow up to 25 K. The potential of transient hole-burning experiments is manifested by the present experiments: g-factors and spin-lattice relaxation times can be measured simultaneously for the ground and the excited state.