Spin Polarization Dynamics of Nonequilibrium Conduction Electrons in Magnetic Junctions

• Published in: Journal of experimental and theoretical physics Vol. 127; no. 6; pp. 1022 - 1032
• Main Authors: Vilkov, E. A., Mikhailov, G. M., Nikitov, S. A., Safin, A. R., Logunov, M. V., Korenivskii, V. N., Chigarev, S. G., Fomin, L. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.12.2018; Springer; Springer Nature B.V
• Subjects: ABSORPTION; Classical and Quantum Gravitation; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Conduction electrons; DENSITY MATRIX; Disorder; ELECTROMAGNETIC FIELDS; Electromagnetism; Electron spin; Electrons; Elementary Particles; EMISSION; EXCHANGE INTERACTIONS; Exchanging; Ferromagnetism; Formalism (Literary criticism); Magnetic induction; MAGNETIC MOMENTS; Magnetism; Order; Particle and Nuclear Physics; Phase Transition in Condensed System; Photons; Physics; Physics and Astronomy; Polarization (spin alignment); Quantum Field Theory; Radiation (Physics); RADIATION SOURCES; Relativity Theory; RELAXATION; Solid State Physics; SPIN; Spin dynamics; SPIN FLIP; SPIN ORIENTATION; Terahertz frequencies
• ISSN: 1063-7761; 1090-6509; 1090-6509
• DOI: 10.1134/S1063776118120105

The dynamics of the motion of the magnetic moment averaged over an ensemble of nonequilibrium spin-injected electrons in a ferromagnetic junction is considered with allowance for the exchange interaction, as well as the interaction with an external electromagnetic field and a thermostat. The solution of this problem is important for the experimental development of compact terahertz-band radiation sources. The rate of quantum transitions of electrons with opposite spins, which determine the spin relaxation under the interaction with a thermostat, is calculated within the density matrix formalism. It is shown that two spin-relaxation modes can be implemented that correspond to low- and high-Q precession of spin-nonequilibrium injected electrons. The effect of the characteristic features of spin-flip transitions under the relaxation of the magnetic moment on the emission and absorption of photons with-energy corresponding to the energy of effective exchange splitting of spin subbands is discussed.