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/Fe

0.73V

0.27(8nm),

with substantially reduced loss rate of G=35 MHz.

Left: Ferromagnetic resonance (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, andW. E. Bailey, Phys. Rev. Lett. 98, 117601* (2007)* Editors' Suggestion

Role of energy loss (damping) in Ghz magnetic devicesW. Bailey, Columbia University, DMR-0239724

Integrated,frequency-agileGHz notch filter(low G: high Q)

CPP read head

Spin momentum transfer

(critical current ~ G)Slonczewski, JMMM

SMT-switched M-RAM

low G

Suppress SMT-noise:

high G

Suppress mag-noise:

low G

N. Smith, APL