Longitudinal resonance for thin film ferromagnets with random anisotropy Academic Article uri icon

abstract

  • 2018 American Physical Society. At the microscopic level, individual spins in ferromagnets with random anisotropy tip transversely with distinct local angles relative to the magnetization M - . When driven by an rf field along the equilibrium M - 0, which changes dM=M0dM - , the transverse tippings rotate about M - 0, corresponding to a new macroscopic collective angle about M - 0. The coupling of dM and leads to a new longitudinal mode that in bulk has a frequency that is largely independent of field H. A longitudinal mode has been observed in thin films of ferromagnets with random anisotropy, but its frequency is H dependent; for H at angle to the film normal and fixed resonator frequency f, Hcos was constant to angles of 80, with H saturating for larger angles. When the demagnetization field is included the theory yields such an H vs for <80, thus providing evidence for the predicted angle . However, lower frequency resonators are needed to manifest the predicted macroscopic anisotropy energy.

published proceedings

  • Physical Review B

author list (cited authors)

  • Saslow, W. M., & Sun, C.

publication date

  • January 1, 2018 11:11 AM