Low Temperature Physics: 41, 9 (2015); https://doi.org/10.1063/1.4906310
Spin-spin relaxation in magnetically dilute crystals
F.S. Dzheparov1,2,3, D.V. Lvov1,2, and M.A. Veretennikov4
1Институт теоретической и экспериментальной физики, г. Москва, 117218, Россия
2Национальный исследовательский ядерный университет «МИФИ», г. Москва, 115409, Россия
3Moscow Institute of Physics and Technology, Dolgoprudny, Institutskii per. 9, Moscow reg., 141700, Russia
4Institute Radio Engineerings and Electronics of the Russian Academy of Science, Moscow, 125009, Russia
Received August 18, 2014
Magnetic resonance in a nuclear paramagnetic system is considered at low spin concentration. Free induction decay (FID) and resonance line shape function (LSF) are calculated. The theory is based on introduction of an auxiliary system where one spin has no flip-flop interaction with surrounding. FID for the spin was calculated using the Anderson–Weiss–Kubo theory, and it’s a memory kernel was applied to construct memory kernel of the main system. Necessary numerical coefficients were obtained from the concentration expansion of FID. The theory was first to take into account the polarization transfer in magnetically dilute systems that produces a substantial slowing down of the decay for times larger than the phase relaxation time. Comparison of the theory with existing experimental results and computer simulations is fulfilled. Satisfactory agreement for the central part of LSF was received after introducing additional broadening existed in the experiments. It is shown that the results of different experiments on magnitude and position of side-band peaks have visible disagreement with one another and with the theory.
PACS: 05.10.–a Computational methods in statistical physics and nonlinear dynamics;
Key words: nuclear magnetic resonance, free induction decay, resonance line shape function, electron paramagnetic resonance, disordered media, magnetically diluted media, spin dynamics, convolution master equation, convolutionless master equation.
Published online: November 24, 2014