Ferromagnetic Resonance at Microwave Frequencies in an Iron Single Crystal

Abstract

Ferromagnetic resonance absorption in a single iron crystal has been observed at 23,675 and 9260 Mc/sec., using an external magnetic field applied perpendicular to the r-f magnetic field in the plane of the crystal surface. A variation in the resonance field is found which depends on the angle the magnetic field makes with the crystal axes. The results agree well with the theory of Kittel which predicts that an angular variation in resonance will result from the effects of crystal anisotropy. In the case of the lower frequency, deviations from the expected angular variation and a second resonance peak are shown to be the result of incomplete alignment of the magnetization with the direction of applied field. A calculation of the first-order anisotropy constant computed on the basis of this deviation agrees well with the known value.