In-plane structural anisotropy of ultrathin Fe films on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>GaAs</mml:mi><mml:mo>(</mml:mo><mml:mn>001</mml:mn><mml:mo>)</mml:mo><mml:mtext>−</mml:mtext><mml:mn>4</mml:mn><mml:mo>×</mml:mo><mml:mn>6</mml:mn></mml:mrow></mml:math>: X-ray absorption fine-structure spectroscopy measurements

Gordon, R. A.; Crozier, E. D.

doi:10.1103/physrevb.74.165405

Cited by 13 publications

(3 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous results on anisotropic damping measured on Fe/InAs(001) have been related to a growth-induced structural anisotropy 19,37 . However, this is not the case for Fe/GaAs(001) since for Fe films thicker than 5 MLs, it is found that there is no in-plane distortion and the structure has fourfold symmetry 38 . We also noticed that the twofold symmetry of the anisotropic damping coincides with the symmetry observed for tunnelling anisotropic magnetoresistance 39 , crystalline anisotropic magnetoresistance 26 and the polar magneto-optic Kerr effect 27 .…”

Section: Discussionmentioning

confidence: 83%

Emergence of anisotropic Gilbert damping in ultrathin Fe layers on GaAs(001)

Chen

Mankovsky²,

Wimmer³

et al. 2018

Nature Phys

View full text Add to dashboard Cite

In the past decades, the damping constant α has been successfully described theoretically-in some cases even quantitatively-using various approaches such as the breathing Fermi-surface model 1,2 , the torque correlation model 3 , scattering theory 4,5 and the torquetorque correlation within a linear response model 6,7 . On the basis of these works, α is expected to scale as α ~ n(E F )ξ 2 τ −1 under certain circumstances, where n(E F ) is the density of states at the Fermi level E F , ξ is the strength of the spin-orbit interaction and τ is the electron momentum scattering time 8,9 . Indeed, the dependences on n(E F ) (refs 9-11 ), ξ (refs 12,13 ) and τ (ref.14 ) have been confirmed separately in a large variety of materials. In general, it is assumed that damping is isotropic. However, several theoretical works [15][16][17][18] have suggested that damping should be anisotropic in single-crystalline ferromagnetic metals, such as bulk Fe, Co and Ni. This prediction is based on the anisotropic electronic structure where the shape of the Fermi surface depends on the orientation of the magnetization direction due to the spin-orbit interaction. The anisotropic electronic structure and thus the anisotropic damping, however, can be dramatically reduced due to smearing of the energy bands in the presence of electron scattering, which makes the experimental observation of the anisotropic damping in bulk materials difficult. So far, only a few experiments [19][20][21][22] have tried to prove the existence of anisotropic damping in bulk magnets but convincing experimental evidence is still lacking.Here, we report the observation of anisotropic Gilbert damping in a quasi-two-dimensional Fe/GaAs(001) system. The idea behind this is to explore the interfacial spin-orbit interaction of a singlecrystalline ferromagnetic metal/semiconductor interface. Our findings differ distinctly from the theoretical predictions made for bulk magnets. The Fe/GaAs heterostructure was intensively studied in the past two decades for semiconductor spintronics, and has been utilized, for example, to realize spin injection at room temperature 23 . Recently, interest in this system has been revived in view of spin-orbit electronics, because of the existence of robust spin-orbit fields at the Fe/GaAs interface, which can cause a mutual conversion between spin and charge currents at room temperature 24 . The spinorbit fields, including both Bychkov-Rashba-and Dresselhaus-like terms, result from the C 2v symmetry of the interface 25 . Specifically, at the Fe/GaAs(001) interface, Fe Bloch states near E F penetrate into GaAs. Therefore, electrons of Fe 'feel' both Bychkov-Rashba and Dresselhaus spin-orbit interaction at the interface, causing a rich variety of interfacial spin-orbit-related phenomena. It has been found, for example, that the symmetry of anisotropic magnetoresistance 26 and the polar magneto-optic Kerr effect 27 of Fe is governed by the twofold interfacial C 2v symmetry rather than its bulk fourfold C 4v symmetry when the thickne...

show abstract

Section: Discussionmentioning

confidence: 83%

Emergence of anisotropic Gilbert damping in ultrathin Fe layers on GaAs(001)

Chen

Mankovsky²,

Wimmer³

et al. 2018

Nature Phys

View full text Add to dashboard Cite

show abstract

“…Such an in-plane lattice strain has been made responsible for the observed strong uniaxial magnetic anisotropy in the thin epitaxial Fe films on GaAs͑001͒ in a recent theory, 67 and was observed experimentally. 55 Future angular dependent CEMS studies at grazing incidence of the ␥ ray could provide information about the preferred direction of the in-plane component V zz .…”

Section: Mössbauer Spectroscopymentioning

confidence: 99%

Epitaxial growth, magnetic properties, and lattice dynamics of Fe nanoclusters on GaAs(001)

et al. 2007

View full text Add to dashboard Cite

Epitaxial bcc-Fe͑001͒ ultrathin films have been grown at ϳ50°C on reconstructed GaAs͑001͒-͑4 ϫ 6͒ surfaces and investigated in situ in ultrahigh vacuum ͑UHV͒ by reflection high-energy electron diffraction, scanning tunneling microscopy ͑STM͒, x-ray photoelectron spectroscopy ͑XPS͒, and 57 Fe conversion electron Mössbauer spectroscopy ͑CEMS͒. For t Fe =1 ML ͑monolayer͒ Fe coverage, isolated Fe nanoclusters are arranged in rows along the ͓110͔ direction. With increasing t Fe the Fe clusters first connect along the ͓−110͔, but not along the ͓110͔ direction at 2.5 ML, then consist of percolated Fe clusters without a preferential orientation at 3 ML, and finally form a nearly smooth film at 4 ML coverage. Segregation of Ga atoms within the film and on the Fe surface appears to occur at t Fe = 4 ML, as evidenced by XPS. For coverages below the magnetic percolation, temperature-dependent in situ CEMS measurements in zero external field provided superparamagnetic blocking temperatures T B of 62± 5, 80± 10, and 165± 5 K for t Fe = 1.9, 2.2, and 2.5 ML, respectively. At T Ͻ T B , freezing of superparamagnetic clusters is inferred from the observed quasilinear T dependence of the mean hyperfine magnetic field ͗B hf ͘. By combining the STM and CEMS results, we have determined a large magnetic anisotropy constant of ϳ5 ϫ 10 5 and ϳ8 ϫ 10 5 J/m 3 at t Fe = 1.9-2.2 and 2.5 ML, respectively. For t Fe ഛ 2.5 ML, our uncoated "free" Fe clusters exhibit intrinsic magnetic ordering below T B , contrary to literature reports on metal-coated Fe clusters on GaAs. Our present results demonstrate that the nature of the percolation transition for free Fe nanoclusters on GaAs͑001͒ in UHV is from superparamagnetism to ferromagnetism. From the Mössbauer spectral area, a very low Debye temperature ⌰ D of 196± 4 K is deduced for these uncoated Fe nanoclusters in UHV, indicating a strong phonon softening in the clusters.

show abstract

“…This result suggests that the origin of in-plane uniaxial anisotropy of bcc Co on GaAs͑001͒ might be mainly generated by the interface lattice shear. 26,27 On the other hand, the fourfold anisotropy seems insensitive to the tiny changes in lattice constant. And the negative sign of bcc Co is determined.…”

mentioning

confidence: 99%

Magnetic anisotropy of bcc Co onFeCu3(001)

Yin

Dong

et al. 2009

Phys. Rev. B

View full text Add to dashboard Cite

Single crystalline body-centered-cubic ͑bcc͒ Co films were achieved on FeCu 3 buffer layer by molecularbeam epitaxy. Fourfold symmetric magnetic hysteresis loops for bcc Co were obtained unambiguously with the easy axes along Co͗110͘. The in-plane uniaxial anisotropy is significantly reduced by FeCu 3 buffer layer. The magnetocrystalline anisotropy constant of bcc Co was further determined to be −1.0ϫ 10 5 erg/ cm 3 by rotational-magneto-optical Kerr effect. Hexagonal-close-packed Co, which would contribute an effective positive K 1 , appeared on top of bcc Co when the film thickness was beyond 0.9 nm. As a result, the magnetocrystalline anisotropy constant of the whole system switched from negative to positive with increasing film thickness.

show abstract

In-plane structural anisotropy of ultrathin Fe films onGaAs(001)−4×6: X-ray absorption fine-structure spectroscopy measurements

Cited by 13 publications

References 39 publications

Emergence of anisotropic Gilbert damping in ultrathin Fe layers on GaAs(001)

Emergence of anisotropic Gilbert damping in ultrathin Fe layers on GaAs(001)

Epitaxial growth, magnetic properties, and lattice dynamics of Fe nanoclusters on GaAs(001)

Magnetic anisotropy of bcc Co onFeCu3(001)

Contact Info

Product

Resources

About