Current-induced noise and damping in nonuniform ferromagnets
Abstract
In the presence of spatial variation in the magnetization direction, electric current noise causes a fluctuating spin-transfer torque that increases the fluctuations of the ferromagnetic order parameter. By the fluctuation-dissipation theorem, the fluctuations at thermal equilibrium are related to the viscous magnetization damping, which in nonuniform ferromagnets acquires a nonlocal tensor structure. At the hand of spin spirals, we demonstrate that the current-induced noise and damping increase with the gradient of the magnetization texture and becomes significant for narrow domain walls.
- Publication:
-
Physical Review B
- Pub Date:
- October 2008
- DOI:
- 10.1103/PhysRevB.78.140402
- arXiv:
- arXiv:0803.2175
- Bibcode:
- 2008PhRvB..78n0402F
- Keywords:
-
- 72.70.+m;
- 72.25.Mk;
- 75.75.+a;
- Noise processes and phenomena;
- Spin transport through interfaces;
- Magnetic properties of nanostructures;
- Condensed Matter - Mesoscale and Nanoscale Physics
- E-Print:
- 5 pages, 1 figure