One of the challenges of building magnetoelectronic devices is obtaining reliable high speed switching of the magnetization direction in these devices. This requires fast response and a damping mechanism, preferably adjustable, that facilitates rapid relaxation towards the new equilibrium magnetization direction. It is well known that the 3d ferromagnetic elements and alloys thereof have small Gilbert damping coefficients, α ≤ 0.01, in the bulk. For instance, an MRAM device with such small damping corresponds to a severely underdamped system, as has been observed in both MTJs and SVs [1,2]. There are different approaches to dealing with this problem. One is to apply carefully engineered magnetic field pulses to switch the device along a desired path. Another, perhaps more crude, is to attempt to increase the magnetization damping hoping that it will not slow down the response too much. I shall review work were Ni$_{80}$Fe$_{20}$ has been alloyed with various elements and the effect this has on damping. I shall also discuss multilayer devices, and some of the changes that come with having more than a single magnetic layer.

[1] R.H. Koch et al., Phys. Rev. Lett. 81, 4512 (1998).

[2] S.E. Russek et al., J. Appl. Phys. 87, 7070 (2000).