Orbital moment anisotropy in ultrathin FePt layers

Soares, Márcio M.; Lamirand, Anne; Ramos, Aline Y.; Santis, M. De; Tolentino, H.

doi:10.1103/physrevb.90.214403

Cited by 11 publications

(3 citation statements)

References 31 publications

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“…Here, the number of the 3d electrons was assumed to be n 3d =6.6. These values are basically consistent with previous studies, [41][42][43] while it has already been argued that there were some systematic discrepancies arising from the errors in the background subtraction procedures. 43 On the other hand, the magnetic moments are estimated to be m spin = 1.53µ B and m orbital = 0.08µ B for the TFY spectra, which exhibited a large discrepancy arising from their strong distortion.…”

supporting

confidence: 92%

Capturing ultrafast magnetic dynamics by time-resolved soft x-ray magnetic circular dichroism

Takubo

Yamamoto

Hikita

et al. 2017

Applied Physics Letters

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Experiments of time-resolved x-ray magnetic circular dichroism (Tr-XMCD) and resonant x-ray scattering at a beamline BL07LSU in SPring-8 with a time-resolution of under 50 ps are presented. A micro-channel plate is utilized for the Tr-XMCD measurements at nearly normal incidence both in the partial electron and total fluorescence yield (PEY and TFY) modes at the L 2,3 absorption edges of the 3d transition-metals in the soft x-ray region. The ultrafast photo-induced demagnetization within 50 ps is observed on the dynamics of a magnetic material of FePt thin film, having a distinct threshold of the photon density. The spectrum in the PEY mode is less-distorted both at the L 2,3 edges compared with that in the TFY mode and has the potential to apply the sum rule analysis for XMCD spectra in pump-probed experiments.Control of electron, magnetic, and lattice states by optical excitations in magnetically ordered materials has attracted considerable attention due to their potential applications in electronic and magnetic recording media functioning on an ultrafast time scale below nanosecond (ns, 10 −9 second, GHz range), since the observation of the ultrafast demagnetization in Ni within 1 picosecond (ps). 1 The ultrafast photo-induced changes of magnetic states are non-equilibrium phenomena and several mechanisms have been proposed to understand them. 2-4 These phenomena generally involve fast structural changes near surface region 5,6 and therefore require cooperative effects, inevitably having a threshold of the photon density.To capture their non-equilibrium dynamics, ultrafast time-resolved experiments have been carried out using ultra-short laser pulses. 3 Recently, the development of a bunched synchrotron light source, 7-11 and x-ray free electron lasers 12-14 have enabled investigation of the dynamic phenomena with element selectivity by tuning the photon energy of the x-ray to the absorption edges of the constituent elements. Especially, time-resolved soft x-ray spectroscopy has many unique characteristics, such as element specificity, chemical specificity and surface sensitivity, which make them versatile for application in a wide range of scientific fields including spintronics and environmental science. Owing to its importance, various time-resolved soft x-ray spectroscopy studies have been carried out. [15][16][17][18][19][20][21] The time-resolved x-ray magnetic circular dichroism (Tr-XMCD) and resonant soft x-ray scattering (Tr-RSXS) measurements for magnetic and electronic materials have been conducted in LCLS, 13,14 ALS, 9 and BESSY II slicing facilities. 10,11,[15][16][17][18][19] The timeresolved x-ray magneto optical Kerr effect (XMOKE) measurements have also been conducted in FERMI. 12 Tr-XMCD measurements at the M absorption below hv <100 eV have also been performed by using high harmonics generation from tabletop lasers in recent years. 22 XMCD at the L 2,3 absorption of 3d transition-metals a) Electronic mail: ktakubo@issp.u-tokyo.ac.jp in the soft x-ray region (hv > 400 eV) is a powerful tool ...

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confidence: 92%

Capturing ultrafast magnetic dynamics by time-resolved soft x-ray magnetic circular dichroism

Takubo

Yamamoto

Hikita

et al. 2017

Applied Physics Letters

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“…In particular, the properties of the OMs are known to be closely related with the properties of the magnetic anisotropy (see, e.g., Refs. [18][19][20][21]. In the case of VI 3 the attention to the OMs is additionally stimulated by the experimental reports of reduced values of the atomic moments and by the physical picture suggested in Ref.…”

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confidence: 99%

Interplay of spin magnetism, orbital magnetism, and atomic structure in layered van der Waals ferromagnet VI$_3$

Sandratskii,

Carva

2021

Preprint

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Recently discovered ferromagnetism of the layered van der Waals material VI3 attracts much research attention. Despite substantial progress, in the following important aspects no consensus has been reached: (i) a possible deviation of the easy axis from the normal to the VI3 layers, (ii) a possible inequivalence of the V atoms, (iii) the value of the V magnetic moments. The theoretical works differ in the conclusions on the conduction nature of the system, the value and the role of the V orbital moments. To the best of our knowledge there is no theoretical works addressing issues (i) and (ii) and only one work dealing with the reduced value of the V moment. By combining the symmetry arguments with density functional theory (DFT) and DFT+U calculations we have shown that the antidimerization distortion of the crystal structure reported by Son et al. [Phys. Rev. B 99, 041402(R) ( 2019)] must lead to the deviation of the easy axis from the normal to the VI3 layers in close correlation with the experimental results. The antidimerization accompanied by the breaking the inversion symmetry leads to the inequivalence of the V atoms. Our DFT+U calculations result in large value ∼0.8 µB of the V orbital moments of the V atoms leading to reduced total V moment in agreement with a number of experimental results and with the physical picture suggested by Yang et al. [Phys. Rev. B 101, 100402(R) ( 2020)]. We obtained large intraatomic noncollinearity of the V spin and orbital moments revealing strong competition between effects coursed by the on-site electron correlation, spin-orbit coupling, and interatomic hybridization since pure intraatomic effects lead to collinear spin and orbital moments. Our calculations confirm the experimental results of strong magnetoelastic coupling revealing itself in the strong dependence of the magnetic properties on the distortion of the atomic structure.

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“…Epitaxial FePt thin films have been extensively investigated for perpendicular magnetic recording media applications due to their high perpendicular magnetic anisotropy [20,21]. The crystal structure of bulk and epitaxial FePt thin films is a chemically ordered body-centered tetragonal cell (L1 0 ) [22][23][24][25][26] at room temperature. This structure can also be described using a face-centered tetragonal (fct) pseudo-cell for which the following lattice parameters have been reported: a FePt = 3.852 Å and c FePt = 3.713 Å.…”

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confidence: 99%

Magnetization reversal modes and coercive field dependence on perpendicular magnetic anisotropy in FePt thin films

Román,

Lopez Pedroso,

Bouzehouane

et al. 2023

J. Phys. D: Appl. Phys.

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The competition between shape and perpendicular magnetic anisotropies in magnetic thin films gives rise to unusual magnetic behaviors. In ferromagnetic thin films, the presence of an out-of-plane component of the magnetic anisotropy may induce a transition from planar to stripe-like magnetic domains above a critical thickness, tc. In this article, we present a detailed study of the magnetization switching mechanism in FePt thin films, where this phenomenon is observed. Using micromagnetic simulations and experiments, we found that below tc the reversal mechanism is well described by the two-phase model while above this thickness the magnetization within each stripe reverses by coherent rotation. We also analyzed the out-of-plane component of the magnetic anisotropy and its temperature dependence, probing that substrate-induced strains are responsible for the abnormal coercive field behavior observed for FePt films with t>tc.

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Orbital moment anisotropy in ultrathin FePt layers

Cited by 11 publications

References 31 publications

Capturing ultrafast magnetic dynamics by time-resolved soft x-ray magnetic circular dichroism

Capturing ultrafast magnetic dynamics by time-resolved soft x-ray magnetic circular dichroism

Interplay of spin magnetism, orbital magnetism, and atomic structure in layered van der Waals ferromagnet VI$_3$

Magnetization reversal modes and coercive field dependence on perpendicular magnetic anisotropy in FePt thin films

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