NMR Study of Solid 3He Droplets In Phase-Separated 3He-4He Mixtures

We report measurements on solid ³ He droplets embedded in a solid ⁴ He matrix. A feature of our experiments is that the mixture crystals, of 1% ³ He concentration, are grown under constant pressure conditions to minimise the formation of defects. Upon cooling the mixture isotopic phase separation is clearly observed in both pressure and NMR data. At a pressure of 36 bar the ³ He separates as solid droplets. NMR measurements on these droplets indicate values of T ₁ and T ₂ similar to those in bulk solid ³ He at the same pressure in the temperature-independent régime. Measurements of the bounded diffusion in the droplets indicate a spin diffusion coefficient similar to that in bulk solid ³ He at the same pressure. These measurements also show the size of the droplets to be a few microns.