2013/03/31 by Yuri P. Kalmykov, Y. P. Kalmykov, W. T. Coffey +6 · 16 citations
Materials Science · Physics and Astronomy · #Condensed matter physics #Langevin equation #Magnetic Properties and Applications #Magnetic field #Magnetic moment #Magnetic properties of thin films #Magnetization #Nanomagnet #Physics #Quantum and electron transport phenomena #Quantum mechanics #Spin (aerodynamics) #Spin polarization #Spin-transfer torque #Thermal fluctuations #Torque #cond-mat.mes-hall #cond-mat.stat-mech
paper · pdf · doi:10.1103/physrevb.88.144406
published in Physical Review B 88(14) (American Physical Society) · an updated version
openalex publication_date 2013/10/07 · arxiv created 2013/10/08 · arxiv updated 2013/10/09 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Thermal fluctuations of nanomagnets driven by spin-polarized currents are treated via the Landau-Lifshitz-Gilbert equation generalized to include both the random thermal noise field and the Slonczewski spin-transfer torque term. By averaging this stochastic (Langevin) equation over its realizations, the explicit infinite hierarchy of differential-recurrence relations for statistical moments (averaged spherical harmonics) is derived for arbitrary demagnetizing factors and magnetocrystalline anisotropy for the generic nanopillar model of a spin-torque device comprising two ferromagnetic strata representing the free and fixed layers and a nonmagnetic conducting spacer all sandwiched between two ohmic contacts. The influence of thermal fluctuations and spin-transfer torques on relevant switching characteristics, such as the stationary magnetization, the magnetization reversal time, etc., is calculated by solving the hierarchy for wide ranges of temperature, damping, external magnetic field, and spin-polarized current, indicating new spin-torque effects in the thermally assisted magnetization reversal comprising several orders of magnitude. In particular, a pronounced dependence of the switching characteristics on the directions of the external magnetic field and the spin polarization exists.