Self consistent solution of micromagnetic and spin diffusion model for spintronic devices
Dr. Dieter Suess
Date & Time: 10:30 - 11:30, October 20th (Tue), 2015.
Place: 8F Medium Seminar Room(#811-812), Sengen
Abstract:
Spin torque oscillators are promising candidates for nano scale frequency generators and amplifiers. Besides their small size, the possibility to tune the frequency is a key feature of these devices. The frequency depends on a variety of parameters including external fields, currents as well as material and geometry of the different magnetic and nonmagnetic layers. Standard micromagnetic simulations employing the spin torque model of Slonczewski [1] are able to predict the frequency depending on the magnetic properties of the material and external fields. However, variation of the geometry requires the adjustment of model specific parameters that are not known upfront and have to be acquired by experiments.
We will present a three-dimensional spin diffusion model self-consistently coupled to the micromagnetic equations that describes spin torque effects based on bulk properties of the different materials including diffusion lengths and polarization parameters [2]. The model inherently allows to describe adiabatic and nonadiabatic spin torque effects and may be applied to spin torque switching of ferromagnetic layers as well as to describe spin torque induced domain wall motion.
Results for spin torque oscillators for different microstructure and geometry will also be presented. In particular the oscillation frequency and tilting angle of the magnetization in the free layer for different pinned layer thicknesses will be shown, which cannot be described by a simple Slonczewski spin torque term.
[1] Slonczewski, John C. "Current-driven excitation of magnetic multilayers." Journal of Magnetism and Magnetic Materials 159.1 (1996): L1-L7.
[2] Zhang, S., P. M. Levy, and A. Fert. "Mechanisms of spin-polarized current-driven magnetization switching." Physical review letters 88.23 (2002): 236601.
We will present a three-dimensional spin diffusion model self-consistently coupled to the micromagnetic equations that describes spin torque effects based on bulk properties of the different materials including diffusion lengths and polarization parameters [2]. The model inherently allows to describe adiabatic and nonadiabatic spin torque effects and may be applied to spin torque switching of ferromagnetic layers as well as to describe spin torque induced domain wall motion.
Results for spin torque oscillators for different microstructure and geometry will also be presented. In particular the oscillation frequency and tilting angle of the magnetization in the free layer for different pinned layer thicknesses will be shown, which cannot be described by a simple Slonczewski spin torque term.
[1] Slonczewski, John C. "Current-driven excitation of magnetic multilayers." Journal of Magnetism and Magnetic Materials 159.1 (1996): L1-L7.
[2] Zhang, S., P. M. Levy, and A. Fert. "Mechanisms of spin-polarized current-driven magnetization switching." Physical review letters 88.23 (2002): 236601.