Magnetization reversal mechanism in La0.67Sr0.33MnO3 thin films on NdGaO3 substrates

Abstract

The field angle dependence of the coercive field of La0.67Sr0.33MnO3 thin films grown epitaxially on NdGaO3 substrates with different crystallographic orientations was determined. All films show uniaxial anisotropy. The angle dependence of the coercivity is best described by a two-phase model, explaining the strong increase in the coercive field for increasing field angles, away from the easy axis direction, as well as the sharp decrease for angles close to the hard direction. This implies that magnetization reversal starts with the depinning of domain walls, analogous to the Kondorsky model. With increasing field the reversal in the domains is not abrupt, but is determined by the gradual displacement of the domain walls. These results are of significance for understanding and possibly engineering of the switching behavior of magnetic tunnel junctions.

Magnetic anisotropy and high-frequency property of flexible FeCoTa films obliquely deposited on a wrinkled topography

“…It is because the two-phase model considers a single-crystal system with an ideal uniaxial anisotropy and predicts H c  = 0 at θ  = 90°. However, for polycrystalline films, the distribution of grain easy axis leads to H c  ≠ 0 at θ  = 90°  40, 42 . Additionally, for our polycrystalline FeCoTa films, the magnetic moments on the wrinkled surface morphology are not strictly parallel to the external magnetic field applied perpendicular to the wrinkles ( θ  = 90°), but make a small angle less than 10°, which also results in H c  ≠ 0 at θ  = 90°.

Figure 3Coercivity H c as a function of magnetic field orientation θ and the corresponding fitting lines by a two-phase model for FeCoTa films grown ( a ) with different pre-strains of 0%, 5%, 20%, 40% and ( b ) with different deposition angles of 0°, 15°, 30°, 45°.

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“…In contrast, the coercivity predicted by the Kondorsky model based on the domain wall nucleation and propagation monotonously increases with increasing θ from 0° to 90° and diverges for θ close to 90°  38 . A two-phase model composed of both coherent rotation and domain wall nucleation is usually employed to account for the magnetization reversal in polycrystalline magnetic films 39–42 . In this model, the application of magnetic field closed to the easy axis results in the nucleation of domain walls.…”

“…For magnetic field applied close to the hard axis, the magnetization coherently rotates. The coercivity in a two-phase system can be described as 40, 42 where N z and N x are the demagnetizing factors in the directions parallel ( θ  = 0°) and perpendicular ( θ  = 90°) to the wrinkles, respectively. N N  =  H k / M s is an effective demagnetizing factor.…”

Magnetization reversal of in-plane uniaxial Co films and its dependence on epitaxial alignment

“…21,46,61 On the other hand, many studies have been performed for the purpose of analyzing the magnetization reversal mechanism in individual ferromagnetic films, including magnetic alloy films. 20,22,26,28,36,42,44,45,49,51,52,55,57 Hereby, many works have been focused on alloys made from 4d/5d transition metals and 3d elemental ferromagnets 14,26,42,49 or alloys of 4f elements with 3d elemental ferromagnets. 17,22,55 These types of alloys, besides having other interesting features, can lead to large magnetocrystalline anisotropies 14 as well as to unconventional magnetic phase transitions as a function of temperature.…”

Магнитные свойства многослойных пленок Co/Pd на пористых темплатах Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- с развитой субструктурой ячеек

“…6, d и f) [38,39], и модифицированной модели Кондорского, характерной для сплошных пленок и их перемагничивания преимущественно путем движения доменных стенок (рис. 6, b) [40,41]. Из сравнения мо-дельных и экспериментальных кривых можно сделать вывод о том, что перемагничивание сплошной пленки корректно описывается в рамках модифицированной мо-дели Кондорского (рис.…”