Spin Kinetics of Liquid 3He in Contact with a DyF3 Micropowder at Ferromagnetic Ordering of Dy3+ Ions

The spin kinetics of liquid He-3 in contact with a mixture of LaF3 (99.67%) and DyF3 (0.33%) micropowders at temperatures of 1.5-3 K has been studied by pulsed nuclear magnetic resonance (NMR). The DyF3 is a dipolar dielectric ferromagnet with the phase transition temperature T (c)= 2.55 K, whereas the diamagnetic fluoride LaF3 is a diluting substance for the optimal observation conditions of (3)DeD mu NMR in powder pores. The magnetic phase transition in DyF3 is accompanied by a considerable change in the character of fluctuations of the magnetic moments of dysprosium ions, which affect the spin kinetics of (3)DeD mu in contact with the substrate. Significant changes in the relaxations rates of the longitudinal and transverse magnetizations of 3DeD mu have been discovered in the region of magnetic ordering of the solid matrix. The technique of studying the static and fluctuating magnetic fields of a solid matrix at low temperatures using liquid He-3 as a probe has been proposed.