A study of the in-phase ("acoustical") and of the out-of-phase ("optical") spin modes in layered ferromagnetic structures with both ferromagnetic and antiferromagnetic coupling is presented, in particular for the system Fe(20 Å)/Cr(20 Å)/Fe(20 Å)/Cr(9 Å)/Fe(100 Å). The "acoustical" mode is the lowest frequency one for low applied fields, but frequency exchanges with the "optical" modes occur at higher fields. It is found that the competition between the Zeeman and the biquadratic exchange terms is responsible for the appearance of a Goldstone mode at a critical field marking a second-order phase transition. The calculated scattering cross-sections are compared to the Brillouin experimental spectra at various external fields.---Presentazione orale by R. Zivieri-conferenza internazionale
"Acoustical" and "optical" spin modes of multilayers with antiferromagnetic coupling and evidence for Goldstone excitations -- Presentazione orale by R. Zivieri - Conferenza internazionale
ZIVIERI, Roberto;GIOVANNINI, Loris;NIZZOLI, Fabrizio
2000
Abstract
A study of the in-phase ("acoustical") and of the out-of-phase ("optical") spin modes in layered ferromagnetic structures with both ferromagnetic and antiferromagnetic coupling is presented, in particular for the system Fe(20 Å)/Cr(20 Å)/Fe(20 Å)/Cr(9 Å)/Fe(100 Å). The "acoustical" mode is the lowest frequency one for low applied fields, but frequency exchanges with the "optical" modes occur at higher fields. It is found that the competition between the Zeeman and the biquadratic exchange terms is responsible for the appearance of a Goldstone mode at a critical field marking a second-order phase transition. The calculated scattering cross-sections are compared to the Brillouin experimental spectra at various external fields.---Presentazione orale by R. Zivieri-conferenza internazionaleI documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
