On the Magnon Spectrum of Antiferromagnetically Aligned Bilayer Films

Puszkarski, H.; Kołodziejczak, Barbara; Akjouj, Abdellatif; Djafari‐Rouhani, Bahram

doi:10.12693/aphyspola.83.677

Cited by 4 publications

(7 citation statements)

References 9 publications

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“…. , 8). We see that modes unaffected by interface coupling (n = 1, 3, 5, 7 for ferromagnetic coupling and n = 2,4,6,8 for antiferromagnetic coupling) have fixed energies, while the modes affected lower their energies as we proceed continuously from strong ferromagnetic coupling to strong antiferromagnetic coupling.…”

Section: "mentioning

confidence: 76%

“…ferromagnetic interface coupling the reverse holds; 5. in the case of decoupled sublayers (JAB/Jb,,, = 0) the spectrum of k-values consists of the roots (8), all being twofold degenerate, as one could expect from physical considerations.…”

Section: "mentioning

confidence: 88%

“…The set of equations (3) has already been solved strictly by applying successively three different approaches: the recurrent interface rescaling approach [8], the interface response-rescaling approach [9], and, quite recently, the transfer matrix approach [ 101. Here, we shall be using the functions u,(k) explicitly expressed by the wave number k in the form given in our paper [ll], which also contains the respective characteristic equation quantizing the mode number k.…”

Section: Standing Spin Wavesmentioning

confidence: 99%

“…for interface modes. The roots of (6a) can be found analytically; they are (8) 71 k = m --. m = 0 , 2 , 4 ,..., ( 2 N -2 ) .…”

Section: Jbulkmentioning

confidence: 99%

“…We see that a given uizaffeected mode is formed by simple repetition of the respective "sublayer" mode; we should keep in mind that this repetition is symmetrical for ferromagnetic, hut antisymmetrical for antiferromagnetic interface coupling. The respective wave numhers k associated with unaffected modes are given by (8).…”

Section: Modes Unaffected Versus Modes Affected By the Interface Coupmentioning

confidence: 99%

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Spectrum of Interface Coupling‐Affected Spin‐Wave Modes in Ferromagnetic Bilayer Films. The Emergence of Interface Mode

Puszkarski

1992

Physica Status Solidi (b)

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A microscopic theory of spin-wave modes in exchange-coupled bilayer films is presented. Using the interface inhomogeneity model (an effective interface exchange coupling parameter is introduced) as well as the Heisenberg model in the spin (exchange and Zeeman) Hamiltonian, an energy dispersion relation and spin-wave mode functions for the exchange-coupled bilayer ferromagnetic films are derived. The theory is valid for Bravais lattices with arbitrary type of film surface/interface orientation at perpendicular (to the film surface) configuration of the static external field and arbitrary ferro/antiferromagnetic value of the interface exchange coupling. The semi-classical picture of the bilayer spin-wave modes is elaborated and the influence of the interface coupling parameter on the shape of the modes is discussed. Then, a detailed discussion of the conditions for the occurrence of interface-localized spin-wave modes is given. The analysis of the interface mode properties is based on the exact solution of the eigenvalue problem of a bilayer film achieved by the interface rescaling approach. Subsequently, a microscopic theory of the ferromagnetic resonance effect in the exchange-coupled bilayer films is developed. It is shown that when intrinsic surface anisotropies are absent the pattern of the resonance spectrum is determined solely by the nature of the interface exchange-coupling integral JAB. When this integral couplesferrornagnetically (JAB > 0) the sublayer spins at the interface, the resonance spectrum consists of only one resonance line which is insensitive to the strength of the coupling. On the contrary, when coupling is antiferromagnetic (JAB < 0), the resonance spectrum is multipeak in nature with the first two (high-field side) lines exhibiting pronounced intensities. When antiferromagnetic coupling is weak, the intensity pattern of these two lines is "regular" (i.e. I, > 12); however, for stronger antiferromagnetic coupling, an inversion of these intensities occurs leading to an "inverted" intensity pattern (Il < 12) in accordance with certain experimental results. Moreover it is shown that inversion of the intensities (caused by negative JAB) is due to the fact that the highest-field line arises by excitation of the mode which is localized on the bilayer interface. It is also shown that this mode represents a bilayer complex vibration formed by the in-phase combination of the sublayer vibrations, and this result corrects the general belief of experimenters that the mode under consideration is due to out-of-phase combination of sublayer vibrations.Eine mikroskopische Theorie der Spin-Wellenmoden in Austausch-gekoppelten diinnen Bi-Schichten wird angegeben. Sowohl mit dem Grenzflachen-Inhomogenitatsmodell (ein effektiver Grenzflachenaustauschkopplungsparameter wird eingefiihrt) als auch mit dem Heisenberg-Modell im (Austausch und Zeeman) Spin-Hamiltonoperator werden eine Energiedispersionsbeziehung und Spinwellenmodenfunktionen fur die austauschgekoppelten diinnen ferromagnetischen Bi-Schichten abgelei...

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Section: "mentioning

confidence: 76%

Section: "mentioning

confidence: 88%

Section: Standing Spin Wavesmentioning

confidence: 99%

“…for interface modes. The roots of (6a) can be found analytically; they are (8) 71 k = m --. m = 0 , 2 , 4 ,..., ( 2 N -2 ) .…”

Section: Jbulkmentioning

confidence: 99%

Section: Modes Unaffected Versus Modes Affected By the Interface Coupmentioning

confidence: 99%

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Spectrum of Interface Coupling‐Affected Spin‐Wave Modes in Ferromagnetic Bilayer Films. The Emergence of Interface Mode

Puszkarski

1992

Physica Status Solidi (b)

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Emergence and inflection angles in the configurational dependence of interface bilayer spin wave energies

Puszkarski¹,

Józefowicz²,

Kołodziejczak³

et al. 1996

Physica Status Solidi (b)

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For the two interface cubic cuts h.c.c. (110) and f.c.c. (111) we consider the existence regions of interface spin waves (ISWs) in a ferromagnetic bilayer filni on the two-dimensional Brillouin zone (BZ) concerning their size and shape versus the respective interface related parameters (interface exchange coupling and intrinsic interface anisotropy), applying the approximation of a very thick bilayer film and the method of Brillouin zone mapping (BZM). We emphasize the effect exerted on the BZM by varying (in the plane perpendicular to the film) the configuration angle 6 of the film magnetization with respect to the film normal. We predict the existence of (at most, two) critical angles 6~ at which the ISWs emerge. The emergence angles are functions of the in-plane wave vector kll of ISW propagation along the interface. We show that the ISW energy varies monotonously with variations of the angle 6 attaining zero slope on the edges of the interval of 6 variability (implying simultaneously the existence of a characteristic point of inflection inside the interval). We prove that the nature of the monotonicity is determined unequivocally by the type of the zntrinsic intrrface anisotropy, namely: the ISW energy grows (decreases) monotonously with the angle 6 if the interface anisotropy is of easy-plane (easy-axis) type. Moreover, we discuss the effects due to the presence of critical and inflection angles with a view to their exploitation in experimental measurements.

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Introduction à une théorie des systèmes composites : exemples simples de matériaux lamellaires

Akjouj¹

1993

Ann. Phys. Fr.

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On the Magnon Spectrum of Antiferromagnetically Aligned Bilayer Films

Cited by 4 publications

References 9 publications

Spectrum of Interface Coupling‐Affected Spin‐Wave Modes in Ferromagnetic Bilayer Films. The Emergence of Interface Mode

Spectrum of Interface Coupling‐Affected Spin‐Wave Modes in Ferromagnetic Bilayer Films. The Emergence of Interface Mode

Emergence and inflection angles in the configurational dependence of interface bilayer spin wave energies

Introduction à une théorie des systèmes composites : exemples simples de matériaux lamellaires

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