Negative remanent magnetization of fine particles with competing cubic and uniaxial anisotropies

Geshev, J.; Viegas, A.D.C.; Schmidt, João Edgar

doi:10.1063/1.368214

Cited by 61 publications

(38 citation statements)

References 24 publications

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“…Details on the calculation procedure are given elsewhere. 40 There is a very good agreement between model and experiment, as can be seen in the figure, confirming the presence of SPM and FM particles, the latter with a certain anisotropy field distribution. The shapes of the hysteresis loops of the irradiated samples, however, show no traces of SPM phase.…”

Section: Hysteresis Loopssupporting

confidence: 67%

Atomic level mixing induced by Kr irradiation of FeCo∕Cu multilayers

Graff

Geshev

Teixeira

et al. 2008

Journal of Applied Physics

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The effects of Kr ion irradiation of FexCo1−x∕Cu multilayers are investigated by means of magnetic and x-ray measurements. The irradiation was performed at room temperature with 600keV of Kr, and the fluences were ranged from 1×1015to5×1015ions∕cm2. X-ray diffraction patterns show that the irradiation was able to produce a significant grain growth and, at the same time, it triggered a strain release. The x-ray absorption measurements around Fe K edge have shown that the FeCo environment changed from bcc, for the as-deposited multilayer, to fcc after appropriate fluence, depending on the Cu thickness and on the Fe∕Co content. For 50Å of Cu, the phase transformation occurs even for the lowest fluence, regardless the Fe∕Co concentration. For 25Å of Cu, it depends on the Fe∕Co concentration. After irradiation, the saturation magnetization suffers a strong decrease, especially for 50Å of Cu. The temperature for the onset of irreversibility also decreases with irradiation, again being the effect stronger for 50Å of Cu. These data indicate that Kr irradiation induced mixing between Cu and FeCo, even though Cu is immiscible with Fe and Co in the equilibrium state.

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Section: Hysteresis Loopssupporting

confidence: 67%

Atomic level mixing induced by Kr irradiation of FeCo∕Cu multilayers

Graff

Geshev

Teixeira

et al. 2008

Journal of Applied Physics

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“…13 This, however, does not result in anomalous hysteresis loops if the magnetization is considered to rotate in the film's plane only, as it is normally assumed in model studies. In some cases, negative remanence for rotation in a plane can be obtained if, e.g., there is asymmetry of the zero-field energy: for predominant uniaxial anisotropy the point of the maximum energy must not be equidistant from the two minima, 19 but this is not the case for the surface in consideration here. Note that in our model the magnetization vector is not constrained to lie in the plane of the film.…”

Section: Resultsmentioning

confidence: 89%

“…Varying the field value, the magnetization curves can be calculated; the two-variable minimization procedure used in the present work is described elsewhere. 19 The anisotropy in the ͑111͒ plane is extremely sensitive to misorientation of the substrate surface with respect to the crystal plane: small tilt is sufficient to completely hide the sixfold anisotropy symmetry. 13 This, however, does not result in anomalous hysteresis loops if the magnetization is considered to rotate in the film's plane only, as it is normally assumed in model studies.…”

Section: Resultsmentioning

confidence: 99%

Origin of the magnetization reversal of an Fe thin film on Si(111)

et al. 2000

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The magnetic behavior of a 60-Å Fe film grown on Si͑111͒ is reported and discussed. Scanning tunneling microcopy images showed Fe stripes along one of the ͗110͘ directions in the ͑111͒ plane, which favors easy magnetization axis parallel to the stripes. Inverted in-plane hysteresis loops and loops with unusual local peaks were measured and interpreted. A phenomenological model was proposed to interpret the magnetization data and an excellent concordance between the experimental and the calculated curves was obtained. The peculiarities in the magnetization curves are directly related to the very small misorientation of the sample's surface from the ͑111͒ plane, and to competing anisotropies. The model calculations showed that the magnetization leaves the sample's plane for small fields, forming an obtuse angle with the field for some configurations, thus resulting in negative remanence, which was confirmed by the nonzero values of the normal to the plane magnetization component from the magneto-optic Kerr effect polarimetry measurements.

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“…The energy minimization procedure used here is described in our previous works. 11,12 In all calculations, the usual room-temperature K 1 and M s values for Fe, i.e., K 1 ϭ4.8ϫ10 5 erg/cm 3 and M s ϭ1708 emu/cm 3 , were used, and n was assumed to be parallel to the ͓111͔ direction.…”

Section: Resultsmentioning

confidence: 99%

“…Our recent works have demonstrated that the observed negative remanent magnetization in such a system can be attributed to a very small misorientation of the Fe layer from the ͑111͒ plane and/or to competing anisotropy effects. 11,12 The aim of the present study was to investigate the relationship between the AF-etched Si͑111͒ substrates preparation conditions ͑with or without subsequent controlled oxidation͒, the morphology of iron films grown onto them, and their magnetic behavior. This was done for two different samples: In one of them, the Fe was deposited onto a bare AF-etched substrate, and the other was deposited onto an AF-etched and subsequently oxidized substrate.…”

Section: Introductionmentioning

confidence: 99%

Strong dependence of the Fe thin-film magnetic anisotropy on the Si(111) substrate preparation

Santos

Geshev

Silva

et al. 2003

Journal of Applied Physics

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We report on the influence of the Si͑111͒ surface preparation on both the structural and the magnetic properties of iron thin films grown onto them. Two different substrate preparation procedures were used, in one of which the substrate was purposely oxidized. The surface analysis was performed by using atomic force and scanning tunneling microscopies, and the magnetic behavior of the films was observed by magneto-optic Kerr effect polarimetry. A strong relationship between the substrate preparation procedure, morphology, and the magnetic response of the iron films was found. A phenomenological model was used to interpret the experimental magnetization data and to derive the anisotropy parameters for both types of Fe samples. It was found that the magnetic response of the film grown onto the oxidized substrate is dominated by the uniaxial anisotropy originated from the substrate topology ͑a terracelike structure͒; the behavior of the other film, grown onto the unoxidized substrate, is determined by both cubic and easy-plane anisotropies.

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Negative remanent magnetization of fine particles with competing cubic and uniaxial anisotropies

Cited by 61 publications

References 24 publications

Atomic level mixing induced by Kr irradiation of FeCo∕Cu multilayers

Atomic level mixing induced by Kr irradiation of FeCo∕Cu multilayers

Origin of the magnetization reversal of an Fe thin film on Si(111)

Strong dependence of the Fe thin-film magnetic anisotropy on the Si(111) substrate preparation

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