Nuclear Magnetic Resonance in RbMnF3

Abstract

A nuclear magnetic resonance study of 85Rb, 87Rb, and 19F in paramagnetic RbMnF3 is reported. The measured shifts of the rubidiumnuclear resonances are the first reported for the case of an alkali nucleus in the paramagnetic XMF3perovskite compounds (X = Na, K, Rb, Cs; M = Mn, Ni, Co). The shift for rubidium is in the opposite direction from that expected from a 5s contact hyperfine interaction. The isotropic hyperfine interaction of the fluorine indicates the presence of 0.51% unpaired 2s spins in the F— orbitals from each Mn+ + neighbor; this result is in good agreement with previous work for the F— resonances in these paramagnetic materials. The anisotropic shift of the F— resonance was examined in a powder sample and a 2p hyperfine coupling coefficient obtained.