Internal Magnetic Fields in Nickel-Rich Nickel-Cobalt Alloys

Abstract

The nuclear magnetic resonances of both the Ni61 nuclei and the Co59 nuclei have been observed in a series of ferromagnetic nickel alloy powders containing up to 2.0 atomic percent cobalt. The room temperature value of the magnetic field at the site of the Co59 nucleus in any of these alloys is found to be about 111 koe, much smaller than the 211-koe field at a Co59 site in pure cobalt. This is also considerably smaller in magnitude than the magnetic field at the nickel site in either the alloy or in pure nickel, which, assuming a Ni61 nuclear moment of 0.30 nuclear magnetons, is about 170 koe. The linewidths of both the nickel and cobalt resonances increase with concentration with no detectable shift in frequency. The temperature dependence of the Co59 resonance frequency in a nickel alloy containing 0.59 atomic percent cobalt has been measured, and found to be different fron that of Ni61 in pure nickel and in the alloy.