Paramagnetic Ce3+ optical emitters in garnets: Optically detected magnetic resonance study and evidence of Gd-Ce cross-relaxation effects

Paramagnetic Ce3+optical emitters have been studied by means of optically detected magnetic resonance (ODMR) via Ce3+ spin-dependent emission in cerium-doped garnet crystals which were both gadolinium free and contain gadolinium in a concentration from the lowest (0.1%) to 100%, i.e., to the superpa...

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Bibliographic Details
Published in:Physical review. B 2017-06, Vol.95 (22), p.224414
Main Authors: Tolmachev, D O, Gurin, A S, Uspenskaya, Yu A, Asatryan, G R, Badalyan, A G, Romanov, N G, Petrosyan, A G, Baranov, P G, Wieczorek, H, Ronda, C
Format: Article
Language:English
Subjects:
Absorption spectra
Cerium
Circular polarization
Cross relaxation
Crystals
Electron spin
Emission
Emitters
Emitters (electron)
Gadolinium
Garnets
Luminous intensity
Magnetic properties
Magnetic resonance
Monitoring
Optical properties
Photoluminescence
Polarization (spin alignment)
Polarized light
Radiation effects
System effectiveness
Ultraviolet radiation
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Summary:Paramagnetic Ce3+optical emitters have been studied by means of optically detected magnetic resonance (ODMR) via Ce3+ spin-dependent emission in cerium-doped garnet crystals which were both gadolinium free and contain gadolinium in a concentration from the lowest (0.1%) to 100%, i.e., to the superparamagnetic state. It has been shown that the intensity of photoluminescence excited by circularly polarized light into Ce3+ absorption bands can be used for selective monitoring the population of the Ce3+ ground-state spin sublevels. Direct evidence of the cross-relaxation effects in garnet crystals containing two electron spin systems, i.e., the simplest one of Ce3+ ions with the effective spin S=12 and the system of Gd3+ ions with the maximum spin S=72, has been demonstrated. Magnetic resonance of Gd3+ has been found by monitoring Ce3+ emission in cerium-doped garnet crystals with gadolinium concentrations of 0.1 at. %, 4%–8%, and 100%, which implies the impact of the Gd3+ spin polarization on the optical properties of Ce3+. Strong internal magnetic fields in superparamagnetic crystals were shown to modify the processes of recombination between UV-radiation-induced electron and hole centers that lead to the recombination-induced Ce3+ emission. Observation of spikes and subsequent decay in the cross-relaxation-induced ODMR signals under pulsed microwave excitation is suggested to be an informative method to investigate transient processes in the many-spin system of Ce3+, Gd3+, and electron and hole radiation-induced centers.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.95.224414