Lowest energy loss in an ultrathin ferromagnetic film William Bailey, Columbia University, DMR-0239724.
Ferromagnetic metals lose energy as their magnetic moments change direction. The minimum rate of energy loss is given by the Gilbert relaxation rate G, a constant for a given metal. For the last 50 years, G has been known to be lowest in Fe, with G=57 MHz.
We have created an epitaxial alloy thin film, MgO/Fe0.73V0.27(8nm), with substantially reduced loss rate of G=35 MHz.
(FMR) linewidth as a function of radio frequency; G is proportional to slope. Bottom: Frequency linewidth f; V-alloy has reduced f.
C. Scheck, L. Cheng, I. Barsukov, Z. Frait, and
W. E. Bailey, Phys. Rev. Lett.98, 117601* (2007)
* Editors' Suggestion
W. Bailey, Columbia University, DMR-0239724
CPP read head
GHz notch filter
(low G: high Q)
N. Smith, APL
Spin momentum transfer
(critical current ~ G)