Ferromagnetic resonance in Terfenol-D at 17 GHz

Ferromagnetic resonance measurements have been performed on several samples of Terfenol-D (Dy0.73Tb0.27Fe1.95) at 16.95 GHz and over the temperature r ange 293 to 305 K. We find that the first magneto crystalline anisotropy co nstant, obtained from one sample under nearly zero stress, is K-1=(-1.4 +/- 1.0) X 10(6) erg/cm(3) at 294 X. Our measurement is distinct from quasistat ic torque measurements in that the lattice does not deform during the measu rement and, hence, the anisotropy contribution due to magnetoelastic strain does not enter. The bare anisotropy constant, unmodified by static elastic strain, is K-1(0)=(+4.4 +/-1.0) X 10(6) erg/cm(3) and dK(1)(0)/dT =(-5.2 /-1.0) X 10(4) erg/K-cm(3). The samples exhibited hysteresis; the position of FMR shifted by 4.0 kOe between measurements made with the magnetic field increasing and those made with the field decreasing.