Memory of low magnetic fields in persistent spectral hole-burning of the [formula omitted] spin-flip transition in NaMgAl(oxalate) 3·9H 2O:Cr(III)

Abstract

The effects of weak magnetic fields (<16 mT) in persistent non-photochemical spectral hole-burning of the R 1-line ( 2 E← 4 A 2 transition) in NaMgAl(oxalate) 3·9H 2O:Cr(III) are reported. The observed hole patterns can be quantitatively rationalized with excited state g-factors, g z ex=1.395±0.015, g x ex=2.00±0.08, and g y ex=1.82±0.08. The deviation from trigonal behavior implies the presence of a significant low symmetry ligand–field. Measuring the hole-burning spectrum in a magnetic field after burning in zero field and vice versa yields the same hole pattern. The latter provides a persistent memory of magnetic fields. Zeeman effects in spectral holes may also be used to stabilize and tune the frequency of single-mode semiconductor lasers.