Accession Number : AD0638910

Title :   MAGNETIC RELAXATION IN RARE EARTH DOPED GARNET.

Corporate Author : CRUFT LAB HARVARD UNIV CAMBRIDGE MASS

Personal Author(s) : Penney,Thomas , III

Report Date : APR 1966

Pagination or Media Count : 234

Abstract : The parallel pump instability (PPI) has been measured in Yb3+ doped YIG. The spin wave linewidth delta H sub k has a broad peak near 100K similar to the resonance linewidth peak. For 0.05% doping the PPI data in the (111) direction fits delta H sub k = 530 csch (28.6/T) + 4.3 csch (4.5+T) from 1.8K to 40K, indicating a Van Vleck-Orbach longitudinal relaxation from two doublets. The 28.6K value is the effective splitting of Yb(3+) doublets on c sites. However, the 4.5K splitting is probably associated with a small number of Yb(3+) ions on a sites. The small effect of 4.5K term is masked in resonance measurements by the constant low temperature linewidth due to two magnon scattering. In contrast, the PPI relaxation rate is independent of two magnon scattering. The 4.5K doublet may well be related to a near crossing of energy levels which probably causes the anomalous low temperature peaks in delta H and resonance field observed by Dillon. (Author)

Descriptors :   (*FERROMAGNETIC MATERIALS, RELAXATION TIME), RARE EARTH ELEMENTS, FERROMAGNETISM, MAGNETIC RESONANCE, YTTERBIUM, TERBIUM, DOPING, YTTRIUM COMPOUNDS, IRON COMPOUNDS, GARNET

Subject Categories : Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE