Couplages ferromagnétiques-antiferromagnétiques : étude des contractions de cycles d'hystérésis à l'aide d'un traceur de cycle très basses fréquences

Schlenker, C.; Paccard, D.

doi:10.1051/jphys:01967002807061100

Cited by 47 publications

(17 citation statements)

References 3 publications

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“…where n is the number of loops traversed, κ is a system dependent constant, and is the exchange bias field in the limit of infinite loops42. Based on this result, this second type of training effect is attributed to the reconfiguration of the AFM moments or domains during the continuous magnetization cycling43.…”

Section: Resultsmentioning

confidence: 94%

Uncoupled surface spin induced exchange bias in α-MnO2 nanowires

Zeng

Sun

et al. 2014

Sci Rep

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We have studied the microstructure, surface states, valence fluctuations, magnetic properties, and exchange bias effect in MnO2 nanowires. High purity α-MnO2 rectangular nanowires were synthesized by a facile hydrothermal method with microwave-assisted procedures. The microstructure analysis indicates that the nanowires grow in the [0 0 1] direction with the (2 1 0) plane as the surface. Mn3+ and Mn2+ ions are not found in the system by X-ray photoelectron spectroscopy. The effective magnetic moment of the manganese ions fits in with the theoretical and experimental values of Mn4+ very well. The uncoupled spins in 3d3 orbitals of the Mn4+ ions in MnO6 octahedra on the rough surface are responsible for the net magnetic moment. Spin glass behavior is observed through magnetic measurements. Furthermore, the exchange bias effect is observed for the first time in pure α-MnO2 phase due to the coupling of the surface spin glass with the antiferromagnetic α-MnO2 matrix. These α-MnO2 nanowires, with a spin-glass-like behavior and with an exchange bias effect excited by the uncoupled surface spins, should therefore inspire further study concerning the origin, theory, and applicability of surface structure induced magnetism in nanostructures.

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Section: Resultsmentioning

confidence: 94%

Uncoupled surface spin induced exchange bias in α-MnO2 nanowires

Zeng

Sun

et al. 2014

Sci Rep

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“…This exchange interaction induces a unidirectional anisotropy as the AF material is cooled through its Néel temperature, T N [1,2]. Exchange-biased bilayers exhibit a number of unusual properties, such as positive exchange bias [3,4], perpendicular coupling [5,6], rotational hysteresis at high fields [7], magnetic training effects [8], measurement dependent loop shifts [9,10], memory effects [11], and asymmetrically shaped hysteresis loops [12][13][14][15].…”

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confidence: 99%

Asymmetric Magnetization Reversal in Exchange-Biased Hysteresis Loops

et al. 2000

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Polarized neutron reflectometry is used to probe the in-plane projection of the net-magnetization vector M of polycrystalline Fe films exchange coupled to twinned (110) MnF 2 or FeF 2 antiferromagnetic (AF) layers. The magnetization reversal mechanism depends upon the orientation of the cooling field with respect to the twinned microstructure of the AF, and whether the applied field is increased to (or decreased from) a positive saturating field; i.e., the magnetization reversal is asymmetric. The reversal of the sample magnetization from one saturated state to the other occurs via either domain wall motion or magnetization rotation on opposite sides of the same hysteresis loop.

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“…In addition to the loop shift and coercivity enhancement described above, several phenomena have also been observed in this process such as the asymmetry of the magnetizing and demagnetizing reversal mechanisms [8,11,12,[16][17][18][19][20][21][22], a training effect [22][23][24][25][26][27], a sweep rate dependence [28,29] and a reduction of the loop shift with respect to zero field after holding the FM layer at negative saturation, i.e. keeping the FM layer saturated in the direction antiparallel to unidirectional easy axis (UEA) of the system [21,22,[28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 95%