NUCLEAR-SPIN INTERACTION IN COPPER - NMR AT HIGH POLARIZATION AND IN LOW FIELDS

We have studied the NMR spectra of the metallic copper in the demagnetized state at temperatures upwards of 50 nK and in external static fields ranging from 0 to 15 mT. At high fields we examine the interference effects between the two isotope (63Cu and 65Cu) lines. At low fields, the absorption line at twice the Larmor frequency is studied for its shift and magnitude. The indirect exchange interaction between the copper nuclear spins is found to correspond to ΣjJij/μ0 h {combining short stroke overlay}2γ2ρ{variant} = -0.42 ± 0.05. © 1979.