Spin-waves in CsMnF3

1977 ◽  
Vol 55 (9) ◽  
pp. 773-778 ◽  
Author(s):  
D. Khatamian ◽  
M. F. Collins
Keyword(s):  
Anisotropy Field ◽  
Wave Dispersion ◽  
Exchange Constant ◽  
High Symmetry ◽  
Nearest Neighbour ◽  
Effective Anisotropy ◽  
Neutron Inelastic Scattering ◽  
Dipole Interactions ◽  
Exchange Constants ◽  
Spin Wave Dispersion

The spin-wave dispersion relations were determined by neutron inelastic scattering for the high symmetry directions (0 0 ξ) and (ξ 0 0) in the hexagonal antiferromagnet CsMnF3. The observed data were satisfactorily fitted to a theoretical model with two nearest-neighbour exchange constants, J12 = 0.134 ± 0.003 THz and J23 = 0.094 ± 0.0105 THz, and with one second-nearest-neighbour exchange constant, J35 = −0.0138 ± 0.003 THz. An effective anisotropy field of −2700 ± 900 Oe along the crystal c axis was also included in the model. This field constrains the spins to the basal plane of the crystal and calculations show that magnetic dipole–dipole interactions can account for its observed magnitude.

Theory of spin waves in triangular antiferromagnets

1978 ◽  
Vol 56 (11) ◽  
pp. 1482-1487 ◽  
Author(s):  
J. A. Oyedele ◽  
M. F. Collins
Keyword(s):  
Spin Wave ◽  
Basal Plane ◽  
Exchange Interactions ◽  
Wave Theory ◽  
Wave Dispersion ◽  
One Dimensional ◽  
Dipole Interactions ◽  
Weak Exchange ◽  
Exchange Constants ◽  
Strong Exchange

A simple hexagonal array of classical spins coupled by nearest-neighbour antiferromagnetic Heisenberg interactions has a ground state with a triangular antiferromagnetic configuration of spins. We have developed spin wave theory for triangular antiferromagnets with both Heisenberg and dipole–dipole interactions. The dipole–dipole interactions confine the spins to the hexagonal basal plane and they do not distort the equiangular triangular structure. Spin wave dispersion relations are plotted for some trial values of the exchange constants. The theory is applied to the triangular antiferromagnet CsMnBr3. This is a quasi-one-dimensional material with strong exchange interactions along the hexagonal axes and with weak exchange interactions within the basal plane that are of the same order as dipolar interactions.

THE VARIATION OF EXCHANGE CONSTANT AND MAGNETOCALORIC EFFECT IN LaFe13-xSix (x = 1.6, 1.9 AND 2.2) COMPOUNDS

2011 ◽  
Vol 25 (25) ◽  
pp. 3303-3313 ◽  
Author(s):  
T. IZGI ◽  
V. S. KOLAT ◽  
H. GENCER ◽  
S. ATALAY
Keyword(s):  
Magnetocaloric Effect ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Wave Dispersion ◽  
Lattice Parameter ◽  
Exchange Constant ◽  
Magnetic Entropy ◽  
Arc Melting ◽  
Exchange Constants ◽  
Si Content

In this work, we present the variation of exchange constant (J exc ) and magnetocaloric effect (MCE) in LaFe 13-x Si x (x = 1.6, 1.9 and 2.2) compounds. NaZn 13-type LaFe 13-x Si x intermetallic compounds were prepared by arc melting in an atmosphere of highly pure argon gas. X-ray results indicated a slight decrease of lattice parameter with increasing Si content. The maximum magnetic entropy change of the LaFe 13-x Si x (x = 1.6, 1.9 and 2.2) samples decreases with increasing Si contents. Also, the magnetic entropy change was calculated theoretically at various magnetic fields and compared with experimental data. The spin-wave dispersion coefficients (D) and exchange constants (J exc ) were calculated for the fist time for these samples. It was found that D and J exc increase with increasing Si content.

Effect of Thickness on Mechanically Tunable Magnetic Anisotropy of FeGa Thin Films Deposited on Flexible Substrates

2015 ◽  
Vol 815 ◽  
pp. 227-232 ◽  
Author(s):  
Ying Yu ◽  
Shu Hong Xie ◽  
Qing Feng Zhan
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Effective Strain ◽  
Anisotropy Field ◽  
Saturation Field ◽  
Effective Anisotropy ◽  
Magnetostriction Constant ◽  
The Difference ◽  
Different Strains

A practical way to manipulate the magnetic anisotropy of magnetostrictive FeGa thin films grown on flexible polyethylene terephthalate (PET) substrates is introduced in this study. The effect of film thickness on magnetic properties and magnetostriction constant of polycrystalline FeGa thin films was investigated. The anisotropy field Hk of flexible FeGa films, i.e., the saturation field determined by fitting the hysteresis curves measured along the hard axis, was enhanced with increasing the tensile strain applied along the easy axis of the thin films, but this enhancement via strain became unconspicuous with increasing the thickness of FeGa films. In order to study the magnetic sensitivity of thin films responding to the external stress, we applied different strains on these films and measure the corresponding anisotropy field. Moreover, the effective magnetostriction constant of FeGa films was calculated from the changes of both anisotropy field and external strain based on the Villari effect. A Neel’s phenomenological model was developed to illustrate that the effective anisotropy field of FeGa thin films was contributed from both the constant volume term and the inverse thickness dependent surface term. Therefore, the magnetic properties for the volume and surface of FeGa thin films were different, which has been verified in this work by using vibrating sample magnetometer (VSM) and magneto-optic Kerr effect (MOKE) system. The anisotropy field contributed by the surface of FeGa film and obtained by MOKE is smaller than that contributed by the film volume and measured by VSM. We ascribed the difference in Hk to the relaxation of the effective strain applied on the films with increasing the thickness of films.

Spin‐Wave Dispersion in KMnF3

1966 ◽  
Vol 37 (3) ◽  
pp. 1054-1055 ◽  
Author(s):  
S. J. Pickart ◽  
M. F. Collins ◽  
C. G. Windsor
Keyword(s):  
Spin Wave ◽  
Wave Dispersion ◽  
Spin Wave Dispersion
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