RESONANCE STUDIES IN FERROMAGNETIC FE2B AND FE2ZR

The hyperfine magnetic fields and quadrupole interactions in Fe2B and Fe2Zr are explored by nuclear magnetic resonance and the Mössbauer effect. The anisotropy found in the Fe2B Mössbauer spectra can be interpreted as a superposition of hyperfine patterns arising from an anisotropic magnetic field and electric field gradient in combination with either two magnetically inequivalent Fe sites (such as was observed in Fe2Zr) or a two-dimensional distribution of magnetization directions. Assuming the former, the two magnetic fields are found to be 252±2 and 244±2 dT at T=4.2 K. The B resonance frequency in Fe2B shows a T32 dependence with some low-temperature deviations which can be understood in terms of a gap arising from magnetocrystalline anisotropy and spin-wave demagnetization. We have extracted the constants of proportionality in the spin-wave approximation, C (the coefficient of the T32 term) and D (the coefficient of the T52 term). We find that DC=(1.0±0.4)×10-3 and that the gap temperature Tg≤1 K. The measured pressure variations aνaP of the B11 and Zr91 frequencies are, respectively, -21±2 and 31±2 Hz bar-1. © 1969 The American Physical Society.