A study of uranium-based multilayers: I. Fabrication and structural characterization

Springell, R.; Zochowski, S.W.; Ward, R. C. C.; Wells, M. R.; Brown, S. D.; Bouchenoire, Laurence; Wilhelm, F.; Langridge, S.; Stirling, W. G.; Lander, G. H.

doi:10.1088/0953-8984/20/21/215229

Cited by 8 publications

(16 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Uranium is a light actinide with itinerant 5f electrons. This property can be exploited in various configurations such as magnetic multilayer systems [21][22][23][24][25]. The SHE of U was experimentally reported [26] and was found to be surprisingly low.…”

Section: Introductionmentioning

confidence: 94%

Spin-dependent transport in uranium

Rossignol

Gradhand

2020

Phys. Rev. B

View full text Add to dashboard Cite

Given the challenges in experimental studies of uranium, the heaviest naturally occurring metal, we present first-principles calculation for the spin-dependent transport. Showing the largest atomic spin-orbit coupling we explore the ability of various crystal phases to maximise the charge to spin conversion using a full relativistic Korringa-Kohn-Rostoker Greens function method. The transport theory is based on a semi classical description where intrinsic and extrinsic, skew scattering, contributions can be separated easily. In addition to the various crystal phases we analyse the effect of substitutional impurities for γ, hcp, as well as the α-phase. We predict a very high, 10 4 (Ωcm) −1 , spin Hall conductivity for the meta-stable hcp-U phase, a giant value 5 times larger than for the conventional spin Hall material Pt. We estimated an efficiency of charge-to-spin current conversion of up to 30%. The spin diffusion length, a crucial parameter in any application, is predicted to be in the range from 3 − 6.5nm, compatible with other charge-to-spin conversion materials. Relating our work to the sparse experimental results, our calculations suggest a γ phase in the thin film rather than the experimentally expected α phase.

show abstract

Section: Introductionmentioning

confidence: 94%

Spin-dependent transport in uranium

Rossignol

Gradhand

2020

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…However, recent modifications to the fabrication procedure have included the introduction of Nb buffer and capping layers and the use of sapphire substrates, which has improved the multilayer quality. Paper I in this series of articles [8] describes the fabrication and structural characterization of U/Fe, U/Co and U/Gd multilayers in detail. The U/TM (TM = transition metal, Fe, Co) systems showed similar growth characteristics to polycrystalline TM and U layers and a critical thickness for crystallinity of ∼20 Å for the TM layers.…”

Section: Introductionmentioning

confidence: 99%

A study of uranium-based multilayers: II. Magnetic properties

Springell

Zochowski

Ward

et al. 2008

J. Phys.: Condens. Matter

Self Cite

View full text Add to dashboard Cite

SQUID magnetometry and polarised neutron reflectivity measurements have been employed to characterise the magnetic properties of U/Fe, U/Co and U/Gd multilayers. The field dependence of the magnetisation was measured at 10K in magnetic fields from -70kOe to 70kOe. A temperature dependent study of the magnetisation evolution was undertaken for a selection of U/Gd samples. PNR was carried out in a field of 4.4kOe for U/Fe and U/Co samples (at room temperature) and for U/Gd samples (at 10K). Magnetic 'dead' layers of ∼ 15Å were observed for U/Fe and U/Co samples, consistent with a picture of interdiffused interfaces. A large reduction in the magnetic moment, constant over a wide range of Gd layer thicknesses, was found for the U/Gd system (∼ 4µ B compared with 7.63µ B for the bulk metal). This could be understood on the basis of a pinning of Gd moments arising from a column-like growth mechanism of the Gd layers. A study of the effective anisotropy suggests that perpendicular magnetic anisotropy could occur in multilayers consisting of thick U and thin Gd layers. A reduction in the Curie temperature was observed as a function of Gd layer thickness, consistent with a finite-size scaling behaviour.

show abstract

“…Thin layers of permalloy (Py; Ni80Fe20) and bilayers of permalloy/uranium (Py/U) were deposited using a dedicated actinide sputter deposition chamber [19]. DC magnetron sputtering was employed to synthesize samples with thicknesses, tPy and tU of 12.5 nm and 3 nm, respectively.…”

mentioning

confidence: 99%

Moderate positive spin Hall angle in uranium

Singh

Anguera

Barco

et al. 2015

Applied Physics Letters

View full text Add to dashboard Cite

We report measurements of spin pumping and the inverse spin Hall effect in Ni80Fe20/Uranium bilayers designed to study the efficiency of spin-charge interconversion in a super-heavy element. We employ broad-band ferromagnetic resonance on extended films to inject a spin current from the Ni80Fe20 (permalloy) into the uranium layer, which is then converted into an electric field by the inverse spin Hall effect. Surprisingly, our results suggest a spin mixing conductance of order 210 19 m -2 and a positive spin Hall angle of 0.004, which are both merely comparable to those of several transition metals. These results thus support the idea that the electronic configuration may be at least as important as the atomic number in governing spin pumping across interfaces and subsequent spin Hall effects. In fact, given that both the magnitude and the sign are unexpected based on trends in d-electron systems, materials with unfilled f-electron orbitals may hold additional exploration avenues for spin physics.

show abstract

A study of uranium-based multilayers: I. Fabrication and structural characterization

Cited by 8 publications

References 25 publications

Spin-dependent transport in uranium

Spin-dependent transport in uranium

A study of uranium-based multilayers: II. Magnetic properties

Moderate positive spin Hall angle in uranium

Contact Info

Product

Resources

About