| 1. |
- Rowan-Robinson, Richard M., et al.
(author)
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The interfacial nature of proximity-induced magnetism and the Dzyaloshinskii-Moriya interaction at the Pt/Co interface
- 2017
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Journal article (peer-reviewed)abstract
- The Dzyaloshinskii-Moriya interaction has been shown to stabilise NSel domain walls in magnetic thin films, allowing high domain wall velocities driven by spin current effects. The interfacial Dzyaloshinskii-Moriya interaction (IDMI) occurs at the interface between ferromagnetic and heavy metal layers with strong spin-orbit coupling, but details of the interaction remain to be understood and the role of proximity induced magnetism (PIM) in the heavy metal is unknown. Here IDMI and PIM are reported in Pt determined as a function of Au and Ir spacer layers in Pt/Co/Au,Ir/Pt. Both interactions are found to be sensitive to sub-nanometre changes in the spacer thickness, correlating over sub-monolayer spacer thicknesses, but not for thicker spacers where IDMI continues to change even after PIM is lost.
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| 2. |
- Ciuciulkaite, Agne, MSc, 1991-, et al.
(author)
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Magnetic and all-optical switching properties of amorphous TbxCo100-x alloys
- 2020
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In: Physical Review Materials. - : American Physical Society (APS). - 2475-9953. ; 4:10
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Journal article (peer-reviewed)abstract
- Amorphous TbxCo100-x magnetic alloys exhibit a list of intriguing properties, such as perpendicular magnetic anisotropy, high magneto-optical activity, and magnetization switching using ultrashort optical pulses. Varying the Tb:Co ratio in these alloys allows for tuning properties such as the saturation magnetic moment, coercive field, and the performance of light-induced magnetization switching. In this paper, we investigate the magnetic, optical, and magneto-optical properties of various TbxCo100-x thin-film alloy compositions. We report on the effect the choice of different seeding layers has on the structural and magnetic properties of TbxCo100-x layers. We also demonstrate that for a range of alloys, deposited on fused silica substrates, with Tb content of 24-30 at. %, helicity-dependent all-optical switching of magnetization can be achieved, albeit in a multishot framework. We explain this property to arise from the helicity-dependent laser-induced magnetization on the Co sublattice due to the inverse Faraday effect. Our paper provides an insight into material aspects for future potential hybrid magnetoplasmonic TbCo-based architectures.
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| 3. |
- Rowan-Robinson, Richard M., et al.
(author)
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Direction-Sensitive Magnetophotonic Surface Crystals
- 2021
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In: Advanced Photonics Research. - : John Wiley & Sons. - 2699-9293. ; 2:10
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Journal article (peer-reviewed)abstract
- Nanometer-thin rare-earth-€“transition-metal (RE-€“TM) alloys with precisely controlled compositions and out-of-plane magnetic anisotropy are currently in the focus for ultrafast magnetophotonic applications. However, achieving lateral nanoscale dimensions, crucial for potential device downscaling, while maintaining designable optomagnetic functionality and out-of-plane magnetic anisotropy is extremely challenging. Herein, nanosized Tb18Co82 ferrimagnetic alloys, having strong out-of-plane magnetic anisotropy, within a gold plasmonic nanoantenna array to design a micrometer-scale magnetophotonic crystal that exhibits abrupt and narrow magneto-optical (MO) spectral features that are both magnetic field and light incidence direction controlled are integrated. The narrow Fano-type resonance arises through the interference of the individual nanoantenna’s surface plasmons and a Rayleigh anomaly of the whole nanoantenna array, in both optical and MO spectra, which are demonstrated and explained using Maxwell theory simulations. This robust magnetophotonic crystal opens the way for conceptually new high-resolution light incidence direction sensors, as well as for building blocks for plasmon-assisted all-optical magnetization switching in ferrimagnetic RE-€“TM alloys.
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| 4. |
- Chioar, Ioan-Augustin, et al.
(author)
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Steering light with magnetic textures
- 2022
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In: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 120:3
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Journal article (peer-reviewed)abstract
- We study the steering of visible light using a combination of magneto-optical effects and the reconfigurability of magnetic domains in yttrium-iron garnet films. The spontaneously formed stripe domains are used as a field-controlled optical grating, allowing for active spatiotemporal control of light. We discuss the basic ideas behind the approach and provide a quantitative description of the field dependence of the obtained light patterns. Finally, we calculate and experimentally verify the efficiency of our magneto-optical grating.
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| 5. |
- Kirschbaum, Miko U.F., et al.
(author)
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Is tree planting an effective strategy for climate change mitigation?
- 2024
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In: Science of the Total Environment. - : Elsevier B.V.. - 0048-9697 .- 1879-1026. ; 909
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Journal article (peer-reviewed)abstract
- The world's forests store large amounts of carbon (C), and growing forests can reduce atmospheric CO2 by storing C in their biomass. This has provided the impetus for world-wide tree planting initiatives to offset fossil-fuel emissions. However, forests interact with their environment in complex and multifaceted ways that must be considered for a balanced assessment of the value of planting trees. First, one needs to consider the potential reversibility of C sequestration in trees through either harvesting or tree death from natural factors. If carbon storage is only temporary, future temperatures will actually be higher than without tree plantings, but cumulative warming will be reduced, contributing both positively and negatively to future climate-change impacts. Alternatively, forests could be used for bioenergy or wood products to replace fossil-fuel use which would obviate the need to consider the possible reversibility of any benefits. Forests also affect the Earth's energy balance through either absorbing or reflecting incoming solar radiation. As forests generally absorb more incoming radiation than bare ground or grasslands, this constitutes an important warming effect that substantially reduces the benefit of C storage, especially in snow-covered regions. Forests also affect other local ecosystem services, such as conserving biodiversity, modifying water and nutrient cycles, and preventing erosion that could be either beneficial or harmful depending on specific circumstances. Considering all these factors, tree plantings may be beneficial or detrimental for mitigating climate-change impacts, but the range of possibilities makes generalisations difficult. Their net benefit depends on many factors that differ between specific circumstances. One can, therefore, neither uncritically endorse tree planting everywhere, nor condemn it as counter-productive. Our aim is to provide key information to enable appropriate assessments to be made under specific circumstances. We conclude our discussion by providing a step-by-step guide for assessing the merit of tree plantings under specific circumstances.
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| 6. |
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| 7. |
- Mishra, K., et al.
(author)
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Ultrafast Demagnetization Control in Magnetophotonic Surface Crystals
- 2022
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 22:23, s. 9773-80
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Journal article (peer-reviewed)abstract
- Magnetic memory combining plasmonics and magnetism is poised to dramatically increase the bit density and energy efficiency of light-assisted ultrafast magnetic storage, thanks to nanoplasmon-driven enhancement and confinement of light. Here we devise a new path for that, simultaneously enabling light driven bit downscaling, reduction of the required energy for magnetic memory writing, and a subtle control over the degree of demagnetization in a magnetophotonic surface crystal. It features a regular array of truncated-nanocone-shaped Au-TbCo antennas showing both localized plasmon and surface lattice resonance modes. The ultrafast magnetization dynamics of the nanoantennas show a 3-fold resonant enhancement of the demagnetization efficiency. The degree of demagnetization is further tuned by activating surface lattice modes. This reveals a platform where ultrafast demagnetization is localized at the nanoscale and its extent can be controlled at will, rendering it multistate and potentially opening up so-far-unforeseen nanomagnetic neuromorphic-like systems operating at femtosecond time scales controlled by light.
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| 8. |
- Rowan-Robinson, Richard M., et al.
(author)
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Efficient current-induced magnetization reversal by spin-orbit torque in Pt/Co/Pt
- 2018
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In: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 124:18
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Journal article (peer-reviewed)abstract
- Current-induced magnetization reversal due to spin-orbit torque is demonstrated in an anisotropy controlled Pt/Co/Pt trilayer. The samples were designed to have weak perpendicular magnetic anisotropy, with a measured anisotropy field of (1340 +/- 20) Oe. Reversal is shown to be dominated by a damping-like torque associated with the spin-Hall effect. A small in-plane magnetic field was required to break the symmetry and enable reversal. With a 273 Oe field, magnetization reversal occurred with a current density amplitude of only 5 x 10(10) Am-2, which is shown to be consistent with a simple model. The field-like torque is negligible, so measurements indicate that the imaginary part of the spin-mixing conductance associated with Co/Pt interfaces must be negligible.
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| 9. |
- Rowan-Robinson, Richard M., et al.
(author)
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Thickness dependent enhancement of the polar Kerr rotation in Co magnetoplasmonic nanostructures
- 2019
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In: AIP Advances. - : American Institute of Physics (AIP). - 2158-3226. ; 9:2
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Journal article (peer-reviewed)abstract
- Large surface plasmon polariton assisted enhancement of the magneto-optical activity has been observed in the past, through spectral measurements of the polar Kerr rotation in Co hexagonal antidot arrays. Here, we report a strong thickness dependence, which is unexpected given that the Kerr effect is considered a surface sensitive phenomena. The maximum Kerr rotation was found to be -0.66 degrees for a 100 nm thick sample. This thickness is far above the typical optical penetration depth of a continuous Co film, demonstrating that in the presence of plasmons the critical lengthscales are dramatically altered, and in this case extended. We therefore establish that the plasmon enhanced Kerr effect does not only depend on the in-plane structuring of the sample, but also on the out-of-plane geometrical parameters, which is an important consideration in magnetoplasmonic device design. (c) 2019 Author(s).
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