Magnetic anisotropies in thick body centered cubic Co

Liu, X.; Stamps, R. L.; Sooryakumar, R.; Prinz, G. A.

doi:10.1063/1.362312

Cited by 12 publications

(7 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have also calculated the MAE of bcc Co with the values of U and J for fcc ͑hcp͒ Co given in Table I. The predicted MAE for bcc Co is Ϫ2.2 ͑Ϫ4.1͒ eV/atom, comparable to the experimental value of ϳϪ1.1 eV/atom, 24 which was obtained by model fitting to the ͑110͒ film.…”

supporting

confidence: 66%

Magnetocrystalline anisotropy and orbital polarization in ferromagnetic transition metals

Xie

Blackman

2004

Phys. Rev. B

View full text Add to dashboard Cite

The magnetocrystalline anisotropy energies ͑MAE's͒ of the ferromagnetic metals bcc Fe, fcc and hcp Co, and fcc Ni have been calculated by using the ab initio tight-binding method. Disentangling the strong correlation among the d orbitals with the Hamiltonian in the local spin-density approximation, we have investigated the orbital polarizations induced by the Hubbard U and Racah B. The experimental MAE of fcc Ni is found with the value of U close to that determined from experiments and used in other theories. With the values of U and J corresponding to the experimental MAE's, the orbital moments for Fe and Co are also in close agreement with experiment.Obtaining the magnetocrystalline anisotropy energies ͑MAE's͒ of Fe, Co, and Ni from ab initio calculations within the local-spin-density approximation ͑LSDA͒ to densityfunctional theory is of considerable current interest. 1-6 From various high-quality LSDA calculations, the best case is Fe, where the computed values differ from experiment by a factor of about 2. The result for hcp Co is far worse, and for Ni, the sign is not even correct. The effect of the so-called spinother-orbit coupling is far too small to bring theory and experiment into accord. 6 The discrepancy between theory and experiment, especially in the case of Ni, is usually attributed to the LSDA.The LSDA predicted MAE's and orbital moments can be improved for Fe and Co ͑Refs. 2 and 7͒ by introducing the Brooks' orbital polarization ͑OPB͒ term 8 which mimics Hund's second rule. However for Ni, the predicted easy axis is still wrong. 2 In OPB, OP is driven by the Racah parameter B, with an energy functional related to the orbital moment ͗L ͘ given by ⌬E OPB ϭϪ 1 2 B͗L ͘ 2 . 9 It was argued that the key

show abstract

supporting

confidence: 66%

Magnetocrystalline anisotropy and orbital polarization in ferromagnetic transition metals

Xie

Blackman

2004

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…The SW stiffness constant of hcp Co has been a subject of controversy. The D NS values of 490–510 meV·Å 2 for hcp Co crystals by the BNL group [ 58 ] were obviously larger than the recent BLS values of D BLS = 430–470 meV·Å 2 [ 63 , 68 , 71 , 73 ].…”

Section: Bls Resultsmentioning

confidence: 88%

“…Various structures of thin Co films, including polycrystalline films [ 63 , 68 ], bcc films [ 69 , 70 , 71 ], and fcc, bcc, and hcp films [ 72 ], have been extensively investigated by BLS since the early stage of the BLS SW studies. One of the most pronounced magnetic properties of Co in the hcp structure is the large uniaxial MAE, which is about one order of magnitude larger than the MAE of cubic Fe and Ni.…”

Section: Bls Resultsmentioning

confidence: 99%

Brillouin Light Scattering from Magnetic Excitations

Yoshihara

2023

Materials

View full text Add to dashboard Cite

Brillouin light scattering (BLS) has been established as a standard technique to study thermally excited sound waves with frequencies up to ~100 GHz in transparent materials. In BLS experiments, one usually uses a Fabry–Pérot interferometer (FPI) as a spectrometer. The drastic improvement of the FPI contrast factor over 1010 by the development of the multipass type and the tandem multipass type FPIs opened a gateway to investigate low energy excitations (ħω £ 1 meV) in various research fields of condensed matter physics, including surface acoustic waves and spin waves from opaque surfaces. Over the last four decades, the BLS technique has been successfully applied to study collective spin waves (SWs) in various types of magnetic structures including thin films, ultrathin films, multilayers, superlattices, and artificially arranged dots and wires using high-contrast FPIs. Now, the BLS technique has been fully established as a unique and powerful technique not only for determination of the basic magnetic constants, including the gyromagnetic ratio, the magnetic anisotropy constants, the magnetization, the SW stiffness constant, and other features of various magnetic materials and structures, but also for investigations into coupling phenomena and surface and interface phenomena in artificial magnetic structures. BLS investigations on the Fe/Cr multilayers, which exhibit ferromagnetic-antiferromagnetic arrangements of the adjacent Fe layer’s magnetizations depending on the Cr layer’s thickness, played an important role to open the new field known as “spintronics” through the discovery of the giant magnetoresistance (GMR) effect. In this review, I briefly surveyed the historical development of SW studies using the BLS technique and theoretical background, and I concentrated our BLS SW studies performed at Tohoku University and Ishinomaki Senshu University over the last thirty five years. In addition to the ferromagnetic SW studies, the BLS technique can be also applied to investigations of high-frequency magnetization dynamics in superparamagnetic (SPM) nanogranular films in the frequency domain above 10 GHz. One can excite dipole-coupled SPM excitations under external magnetic fields and observe them via the BLS technique. The external field strength determines the SPM excitations’ frequencies. By performing a numerical analysis of the BLS spectrum as a function of the external magnetic field and temperature, one can investigate the high-frequency magnetization dynamics in the SPM state and determine the magnetization relaxation parameters.

show abstract

“…Brillouin light scattering shows that uniaxial anisotropy dominates the total magnetocrystalline anisotropy and produces an easy axis along the ͓100͔ direction. 10 In addition, polarized neutron reflection ͑PNR͒ measures a reduced magnetic moment of 1.0 B near the Co/ GaAs interface and 1.7 B near the center of the film. 11 A more complete understanding of the magnetic properties of thin bcc-Co films has been hindered by the difficulty of preparing high-quality films for measurement due to the reactivity of the Co/ GaAs͑110͒ system.…”

mentioning

confidence: 99%

“…The anisotropies for a 35.7-nm-thick bcc-Co film are K 1 = −4.5ϫ 10 4 J/m 3 , and K u = 9.0ϫ 10 4 J/m 3 , as measured by Brillouin light scattering. 10 Due to the large thickness of the film, the measured anisotropies may be used as good estimates of the bulk anisotropies. Substitution of these values, and t SRT = 7.3 ML into Eq.…”

mentioning

confidence: 99%

Magnetic properties ofCo∕GaAs(110)

Monchesky

Unguris

2006

Phys. Rev. B

View full text Add to dashboard Cite

We observed three magnetic states of an ultrathin, atomically well-ordered Co film grown on a cleaved GaAs͑110͒ substrate. For a Co thickness less than 3.4 monolayers ͑ML͒, we find a ferromagnetically dead layer associated with the formation of interfacial Co 2 GaAs. For thicknesses greater than 4.1 ML, the Co film grows with a bcc structure that contains 6 at. % Ga. The films are ferromagnetic with an easy axis along the ͓110͔ direction. This magnetic state persists up to a thickness of 7 ML, at which point an abrupt in-plane spin-reorientation transition reorients the magnetization along the ͓001͔ direction.

show abstract

Magnetic anisotropies in thick body centered cubic Co

Cited by 12 publications

References 13 publications

Magnetocrystalline anisotropy and orbital polarization in ferromagnetic transition metals

Magnetocrystalline anisotropy and orbital polarization in ferromagnetic transition metals

Brillouin Light Scattering from Magnetic Excitations

Magnetic properties ofCo∕GaAs(110)

Contact Info

Product

Resources

About