First-principles prediction of enhanced magnetic anisotropy in FeCo alloys

Wu, Dien; Zhang, Qiming; Liu, J. Ping; Yuan, Dingwang; Wu, Ruqian

doi:10.1063/1.2840721

Cited by 28 publications

(13 citation statements)

References 22 publications

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“…The presence of a finite coercive field and a higher remanent magnetisations in FeCo alloy nanoparticles compared to Co nanoparticles of the same size (and deposited under the same conditions onto identical substrates) is unexpected. FeCo alloys are usually soft magnetic materials with very high saturation magnetisation fields and very low coercive fields 47. Thus, the respective magnetic anisotropy energies should be very small, at least much smaller than those of Co.…”

Section: Resultsmentioning

confidence: 99%

Magnetism of 3d transition metal nanoparticles on surfaces probed with synchrotron radiation – from ensembles towards individual objects

Bansmann

Kleibert

Getzlaff

et al. 2010

Physica Status Solidi (b)

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Mass-filtered Fe, Co and FeCo nanoparticles in the size regime from 7 to 25 nm have been deposited under soft-landing conditions onto ferromagnetic films, non-magnetic surfaces as well as embedded into Al matrices. In situ X-ray magnetic circular dichroism (XMCD) measurements reveal a ferromagnetic behaviour of FeCo nanoparticles (size: 10 nm) on Sisubstrates at room temperature whereas the respective Co nanoparticles are superparamagnetic. Besides measurements on ensembles of nanoparticles, we have also carried out in situ measurements on individual Fe nanoparticles using X-ray photoemission electron microscopy at the Fe L 3,2 edges. Fe nanoparticles on Co films show a magnetic contrast depending on the direction of the underlying poly-crystalline Co domains. This technique also allows to record XMCD spectra on individual nanoparticles.Spectroscopy and spectro-microscopy on magnetic particles.

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Section: Resultsmentioning

confidence: 99%

Magnetism of 3d transition metal nanoparticles on surfaces probed with synchrotron radiation – from ensembles towards individual objects

Bansmann

Kleibert

Getzlaff

et al. 2010

Physica Status Solidi (b)

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“…Note that Wu et al . have shown that the binding energy/cell (−0.51 eV/cell) is minimum for (FeCo) 8 cluster when it is in bcc configuration30. Following the thermal spike temperatures raised in respective fluences, we have performed ab initio molecular dynamics (MD) simulations under the frame work of DFT to first understand the structural changes of the bcc (FeCo) 8 cluster at those temperatures (i.e.…”

Section: Resultsmentioning

confidence: 99%

Triggering of spin-flipping-modulated exchange bias in FeCo nanoparticles by electronic excitation

Sarker

Bhattacharya

Srivastava

et al. 2016

Sci Rep

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The exchange coupling between ferromagnetic (FM)-antiferromagnetic (AF) interfaces is a key element of modern spintronic devices. We here introduce a new way of triggering exchange bias (EB) in swift heavy ion (SHI) irradiated FeCo-SiO2 films, which is a manifestation of spin-flipping at high irradiation fluence. The elongation of FeCo nanoparticles (NPs) in SiO2 matrix gives rise to perpendicular magnetic anisotropy at intermediate fluence. However, a clear shift in hysteresis loop is evident at the highest fluence. This reveals the existence of an AF exchange pinning domain in the NPs, which is identified not to be oxide shell from XANES analysis. Thermal spike calculations along with first-principles based simulations under the framework of density functional theory (DFT) demonstrate that spin flipping of 3d valence electrons is responsible for formation of these AF domains inside the FM NPs. EXAFS experiments at Fe and Co K-edges further unravel that spin-flipping in highest fluence irradiated film results in reduced bond lengths. The results highlight the possibility of miniaturization of magnetic storage devices by using irradiated NPs instead of conventionally used FM-AF multilayers.

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“…Furthermore, for FeCo monolayers epitaxially grown on MgO (001), the in-plane lattice is enlarged to match that of MgO(001) ( a = 2.97 Å), while the out-of-plane lattice is shortened to 2.71 Å, leading to a c / a ratio of 0.91. It has been reported that the MAE reduces as the c / a ratio decreases and becomes negative when it is smaller than 1 for B2-FeCo alloy [ 28 ]. Hence, a negative MAE is anticipated in Fe 8 Co 8 /MgO.…”

Section: Resultsmentioning

confidence: 99%

First-principles calculations of perpendicular magnetic anisotropy in Fe1−x Co x /MgO(001) thin films

Cai

Guo

et al. 2015

Nanoscale Res Lett

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The perpendicular magnetic anisotropy (PMA) of Fe1−xCox thin films on MgO(001) was investigated via first-principles density-functional calculations. Four different configurations were considered based on their ground states: Fe/MgO, Fe12Co4/MgO, Fe10Co6/MgO, and Fe8Co8/MgO. As the Co composition increases, the amplitude of PMA increases first from Fe/MgO to Fe12Co4/MgO, and then decreases in Fe10Co6/MgO; finally, the magnetic anisotropy becomes horizontal in Fe8Co8/MgO. Analysis based on the second-order perturbation of the spin-orbit interaction was carried out to illustrate the contributions from Fe and Co atoms to PMA, and the differential charge density was calculated to give an intuitive comparison of 3d orbital occupancy. The enhanced PMA in Fe12Co4/MgO is ascribed to the optimized combination of occupied and unoccupied 3d states around the Fermi energy from both interface Fe and Co atoms, while the weaker PMA in Fe10Co6/MgO is mainly attributed to the modulation of the interface Co-dxy orbital around the Fermi energy. By adjusting the Co composition in Fe1−xCox, the density of states of transitional metal atoms will be modulated to optimize PMA for future high-density memory application.

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First-principles prediction of enhanced magnetic anisotropy in FeCo alloys

Cited by 28 publications

References 22 publications

Magnetism of 3d transition metal nanoparticles on surfaces probed with synchrotron radiation – from ensembles towards individual objects

Magnetism of 3d transition metal nanoparticles on surfaces probed with synchrotron radiation – from ensembles towards individual objects

Triggering of spin-flipping-modulated exchange bias in FeCo nanoparticles by electronic excitation

First-principles calculations of perpendicular magnetic anisotropy in Fe1−x Co x /MgO(001) thin films

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