Anomalous spin diffusion in ferromagnetic spin systems
Affiliation:
1. Impax Inc., 31047 Genstar Road, Hayward, CA 94544, USA;2. Acorn NMR Inc., 7670 Las Positas Road, Livermore, CA 94551, USA;1. Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK;2. Scientific Computing Department, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX, UK;3. Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK;1. TIFR Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 21 Brundavan Colony, Narsingi, Hyderabad 500075, India;2. Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India;1. School of Materials Science and Engineering, Pusan National University, Busan 609-735, South Korea;2. Integrative Graduate Program of Ship and Offshore Plant Technology for Ocean Energy Resource, Pusan National University, Busan 609-735, South Korea;3. Korea Institute of Industrial Technology, Busan 618-230, South Korea;1. Department of Mathematics, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, PR China;2. Faculty of Mathematics, Kyushu University, Fukuoka 819-0395, Japan
Abstract:
The problem of spin diffusion in ferromagnetic Heisenberg spin systems in paramagnetic region near the Curie point is studied using the method developed for treating the transport coefficients exhibiting anomalous peaks near the critical point. The conventional theory of the critical slowing-down is found to be inadequate for this problem, and the self-consistent treatment for the generalized diffusion coefficient is presented. The result predicts that the diffusion constant in paramagnetic region vanishes like x−(14) role=presentation style=font-size: 90%; display: inline-block; position: relative;> instead of x−1 near the Curie point where x the magnetic susceptibility. The reason for this peculiarity is discussed in relation to the somewhat related problem of the molecular diffusion in critical mixtures where the conventional theory seems to hold. The theory also predicts a strong dependence of the spin diffusion coefficient on the wave vector and frequency of an applied disturbance.
