Nuclear Magnetic Resonance in Nickel-Fluosilicate between 0.15°K and 4.2°K

Abstract

Proton and fluorine nuclear resonance in nickel-fluosilicate were studied in the paramagnetic region of temperatures between 0.15°K and 4.2°K. Temperatures below one degree were obtained by the magnetic cooling of the sample itself. From the temperature dependence of the shift, the sign of the exchange interaction between Ni⁺⁺ ions was found to be ferromagnetic. The order of magnitude of the observed shift was well explained by the dipolar field alone. The signals disappeared when the temperature went below the Curie point.