Observation of Macroscopic Heat Transfer by a Nuclear Spin System and Measurement of the Spin Diffusion Constant

Abstract

Experiments are reported which measure directly the macroscopic transfer of energy from the surface of small crystallites to the interior via nuclear spins. The hydrogen nuclei in Y${\left({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{S}{\mathrm{O}}_4\right)}_3$·9${\mathrm{H}}_2$O constitute the nuclear spin system that transports the energy. We directly determine the value 5×${10}^{-12\mathrm{}}$ ${\mathrm{cm}}^2$/sec (±20%) for the spin diffusion constant, which does not depend on the correctness of any theory of nuclear spin-lattice relaxation.