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Quantum‐Mechanical Treatment of the Transient Processes with Three‐Magnon Non‐Linear Transitions under Perpendicular Pumping
Author(s) -
Le Gall H.
Publication year - 1968
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19680280206
Subject(s) - magnon , physics , excitation , transient (computer programming) , quantum electrodynamics , quantization (signal processing) , condensed matter physics , spins , quantum mechanics , mathematics , algorithm , ferromagnetism , computer science , operating system
The transient growth of spin‐wave populations with three‐magnon non‐linear processes under perpendicular pumping is studied. Calculations are made on the basis of second quantization of the magnetic system and the pumping microwave field, assuming that the magnons are in thermal distribution before the electromagnetic pulse is applied. General expressions describing transient evolution of the uniform mode and the parametric states are established in the case where the coincidence condition is satisfied (occurrence of the three‐magnon transitions at resonance). The stationary state of the parametric magnons is also determined. To test experimentally the validity of the theory an expression for the transient power absorbed by the crystal at the beginning of the parametric excitation of the quasiparticles is derived. Basing on experimental data, the limits of the applicability of the theory are discussed.