Premium
Magnon energy gap and the magnetically structural symmetry in a three‐layer ferrimagnetic superlattice
Author(s) -
Qiu Rongke,
Zhang Zhidong,
Guo Lianquan,
Ying Caihong,
Liang Jing
Publication year - 2006
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.200541477
Subject(s) - superlattice , magnon , condensed matter physics , brillouin zone , ferrimagnetism , spin wave , symmetry (geometry) , band gap , physics , electronic band structure , spin (aerodynamics) , magnetization , ferromagnetism , quantum mechanics , magnetic field , geometry , thermodynamics , mathematics
The magnon energy band in a ferrimagnetic superlattice with three layers in a unit cell is studied by employing retarded Green's functions and the spin‐wave method. Two modulated energy gaps Δ ω 13 and Δ ω 23 are evaluated systematically, which exist in the magnon energy band along the K x ‐direction perpendicular to the plane of the superlattice. It is revealed that the energy gap Δ ω 13 has a direct relation with the symmetry among the spin quantum numbers and the interlayer exchange couplings, while the energy gap Δ ω 23 relates to the symmetry among these spin quantum numbers only. These symmetries differ from the symmetry of crystallographic point groups. We define the magnetically structural symmetry that is dominated mainly by the magnetic parameters. The absence of the energy gap at a certain condition means that the system has a high magnetically structural symmetry. The magnetically structural symmetry of the superlattice, which is an intrinsic property, strongly affects the magnon energy band structure and thus the magnetic behaviors of the system. Furthermore, two complete bandgaps are observed to extend through the Brillouin zone (referred to as “magnonic crystal”) in this superlattice system. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)