Dopants for independent control of precessional frequency and damping in Ni[sub 81]Fe[sub 19] (50 nm) thin films

Reidy, S. G.; Cheng, L.; Bailey, W. E.
February 2003
Applied Physics Letters;2/24/2003, Vol. 82 Issue 8, p1254
Academic Journal
Dilute impurities can be used to control the dynamical response of ferromagnetic thin film magnetization at frequencies >1 GHz. Central lanthanide dopants (Sm, Eu, Tb, Dy, and Ho) have been investigated for their effect on the magnetization dynamics of Ni[SUB81]Fe[SUB19](50 nm). We find that Sm, Dy, and Ho contribute an increase on damping α up to four times stronger per concentration than that provided by Tb, with minimal effect on precessional frequency. One dopant, Eu, leaves α unchanged but boosts the resonant frequency f[SUBp] of the system by ∼500 MHz for 3% addition, equivalent to a dynamic anisotropy field of 9 Oe, "stiffening" the system. The results indicate that precessional frequency and damping may be controlled independently in magnetoelectronic device materials.


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