We present new and refined data for the magnetic field (H) and temp. (T) dependence of the proton spin-lattice relaxation rate (1/T1) in antiferromagnetic mol. rings as well as a new explicit scaling formula that accurately reproduces our data. The key ingredients of our formulation are (1) a reduced relaxation rate, R(H,T)=(1/T1)/(Tχ(T)), given by R(H,T)=Aωc(T)/(ω2c(T)+ω2N), where χ=(dM/dH)T is the differential susceptibility, A is a fitting const., and ωN is the proton Larmor frequency, and (2) a temp.-dependent correlation frequency ωc(T) which at low T is given by ωc(T).proportional to.Tα, that we identify as a lifetime broadening of the energy levels of the exchange-coupled paramagnetic spins due to spin-acoustic phonon coupling. The main consequences are (1) R(H,T) has a local max. for fixed H and variable T that is proportional to 1/H; the max. occurs at the temp. T0(H) for which ωc(T)=ωN; (2) for low T a scaling formula applies, R(H,T)/R(H,T0(H))=2tα/(1+t2α), where t = T/T0(H). Both results are confirmed by our exptl. data for the choice α=3.5±0.5.

Scaling Behavior of the Proton Spin-lattice Relaxation Rate in Antiferromagnetic Molecular Rings / S. H., Baek; M., Luban; A., Lascialfari; E., Micotti; Y., Furukawa; F., Borsa; J., VAN SLAGEREN; Cornia, Andrea. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - STAMPA. - 70:(2004), pp. 134434/1-134434/5.

Scaling Behavior of the Proton Spin-lattice Relaxation Rate in Antiferromagnetic Molecular Rings

CORNIA, Andrea
2004

Abstract

We present new and refined data for the magnetic field (H) and temp. (T) dependence of the proton spin-lattice relaxation rate (1/T1) in antiferromagnetic mol. rings as well as a new explicit scaling formula that accurately reproduces our data. The key ingredients of our formulation are (1) a reduced relaxation rate, R(H,T)=(1/T1)/(Tχ(T)), given by R(H,T)=Aωc(T)/(ω2c(T)+ω2N), where χ=(dM/dH)T is the differential susceptibility, A is a fitting const., and ωN is the proton Larmor frequency, and (2) a temp.-dependent correlation frequency ωc(T) which at low T is given by ωc(T).proportional to.Tα, that we identify as a lifetime broadening of the energy levels of the exchange-coupled paramagnetic spins due to spin-acoustic phonon coupling. The main consequences are (1) R(H,T) has a local max. for fixed H and variable T that is proportional to 1/H; the max. occurs at the temp. T0(H) for which ωc(T)=ωN; (2) for low T a scaling formula applies, R(H,T)/R(H,T0(H))=2tα/(1+t2α), where t = T/T0(H). Both results are confirmed by our exptl. data for the choice α=3.5±0.5.
70
134434/1
134434/5
Scaling Behavior of the Proton Spin-lattice Relaxation Rate in Antiferromagnetic Molecular Rings / S. H., Baek; M., Luban; A., Lascialfari; E., Micotti; Y., Furukawa; F., Borsa; J., VAN SLAGEREN; Cornia, Andrea. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - STAMPA. - 70:(2004), pp. 134434/1-134434/5.
S. H., Baek; M., Luban; A., Lascialfari; E., Micotti; Y., Furukawa; F., Borsa; J., VAN SLAGEREN; Cornia, Andrea
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/450577
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