2024/02/07 by Chen Sun, Wayne M. Saslow, Sun, Chen +1
Biochemistry, Genetics and Molecular Biology · Engineering · #Characterization and Applications of Magnetic Nanoparticles #FOS: Physical sciences #Geomagnetism and Paleomagnetism Studies #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · pdf · doi:10.48550/arxiv.2402.04639
openalex publication_date 2024/02/07 · openalex created_date 2024/02/09 · openalex updated_date 2026/07/28
In metals with finite magnetization M, experiment shows that transverse polarized dc spin currents Ji both decay and precess on crossing a finite sample thickness. The present work uses Onsager's irreversible thermodynamics, with M and Ji as fundamental variables, to develop a theory with aspects of the Landau-Lifshitz theory solely for the M of (charged) electronic ferromagnets, and of the Leggett theory for the M and Ji of (uncharged) nuclear paramagnets. As for the ferromagnet of Landau-Lifshitz, ∂tM includes a characteristic decay time τM. As for the nuclear paramagnet, ∂tJi includes a characteristic decay time τJ, is driven by the gradient of a (vector) spin pressure, and precesses about a mean-field proportional to M. The spin pressure has a coefficient G proportional to a velocity squared, and D0≡ (1)/(2)GτJ serves as an effective diffusion coefficient. These equations apply when spin currents are generated. Using the derived dynamical equations for the magnetization and for the spin current, we obtain the steady state (dc limit) solution whose transverse wavevector squared is complex, with real part from diffusion and imaginary part from precession. The ac case is also considered.