Effects of low magnetic fields in transient spectral hole-burning of the R 1-line in emerald, Be 3Al 2Si 6O 18:Cr(III)

Abstract

Polarized transient spectral hole-burning in the R 1-line ( 2 A ̄ ( 2E) ← 4A 2) 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 ⊥( 4A 2)=1.96 ± 0.02, g ∥( 4A 2)=1.97 ± 0.02 and g ∥[ 2 A ̄ ( 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 2 A ̄ ( 2E) levels at temperatures >8 K on the 2.5 ms experimental timescale but thermalization between the ±3/2 4A 2 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.