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Bauer, T.A. (author), Davis, Timothy J. (author), Frank, Bettina (author), Dreher, Pascal (author), Janoschka, David (author), Meiler, Tim C. (author), Meyer zu Heringdorf, Frank J. (author), Kuipers, L. (author), Giessen, Harald (author)The creation and manipulation of optical vortices, both in free space and in two-dimensional systems such as surface plasmon polaritons (SPPs), has attracted widespread attention in nano-optics due to their robust topological structure. Coupled with strong spatial confinement in the case of SPPs, these plasmonic vortices and their underlying...journal article 2023
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Arora, S. (author), Bauer, T.A. (author), Parappurath, N. (author), Barczyk, R.T. (author), Verhagen, E. (author), Kuipers, L. (author)We measure the local near-field spin in topological edge state waveguides that emulate the quantum spin Hall effect. We reveal a highly structured spin density distribution that is not linked to a unique pseudospin value. From experimental near-field real-space maps and numerical calculations, we confirm that this local structure is essential...journal article 2022
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Barczyk, R.T. (author), Parappurath, N. (author), Arora, S. (author), Bauer, T.A. (author), Kuipers, L. (author), Verhagen, E. (author)We study the signatures of topological light confinement in the leakage radiation of two-dimensional topological photonic crystal cavities that feature the quantum spin Hall effect at telecom wavelengths. The mode profiles in real and momentum space are retrieved using far field imaging and Fourier spectropolarimetry. We examine the scaling...conference paper 2022
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Bertelli, I. (author), Simon, B.G. (author), Yu, T. (author), Aarts, Jan (author), Bauer, G.E. (author), Blanter, Y.M. (author), van der Sar, T. (author)Spin waves in magnetic insulators are low-damping signal carriers that can enable a new generation of spintronic devices. The excitation, control, and detection of spin waves by metal electrodes is crucial for interfacing these devices to electrical circuits. As such, it is important to understand metal-induced damping of spin-wave transport,...journal article 2021
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Díaz-Escobar, Evelyn (author), Bauer, T.A. (author), Pinilla-Cienfuegos, Elena (author), Barreda, Ángela I. (author), Griol, Amadeu (author), Kuipers, L. (author), Martínez, Alejandro (author)High-index nanoparticles are known to support radiationless states called anapoles, where dipolar and toroidal moments interfere to inhibit scattering to the far field. In order to exploit the striking properties arising from these interference conditions in photonic integrated circuits, the particles must be driven in-plane via integrated...journal article 2021
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Arora, S. (author), Bauer, T.A. (author), Barczyk, René (author), Verhagen, Ewold (author), Kuipers, L. (author)Topological on-chip photonics based on tailored photonic crystals (PhCs) that emulate quantum valley-Hall effects has recently gained widespread interest owing to its promise of robust unidirectional transport of classical and quantum information. We present a direct quantitative evaluation of topological photonic edge eigenstates and their...journal article 2021
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de Angelis, L. (author), Bauer, T.A. (author), Alpeggiani, F. (author), Kuipers, L. (author)When the positions of two generic singularities of equally signed topological index coincide, a higher-order singularity with twice the index is created. In general, singularities tend to repel each other when sharing the same topological index, preventing the creation of such higher-order singularities in 3D generic electromagnetic fields....journal article 2019
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Spaeth, Patrick (author), Adhikari, Subhasis (author), Le, Laurent (author), Jollans, Thomas (author), Pud, S. (author), Albrecht, Wiebke (author), Bauer, T.A. (author), Caldarola, M. (author), Kuipers, L. (author), Orrit, Michel (author)Circular dichroism (CD) spectroscopy is a powerful optical technique for the study of chiral materials and molecules. It gives access to an enantioselective signal based on the differential absorption of right and left circularly polarized light, usually obtained through polarization analysis of the light transmitted through a sample of...journal article 2019
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Geprägs, S. (author), Kehlberger, A. (author), Coletta, F.D. (author), Qiu, Z. (author), Guo, E.J. (author), Schulz, T. (author), Mix, C. (author), Meyer, S. (author), Kamra, A. (author), Althammer, M. (author), Huebl, H. (author), Jakob, G. (author), Ohnuma, Y. (author), Adachi, H. (author), Barker, J. (author), Maekawa, S. (author), Bauer, G.E.W. (author), Saitoh, E. (author), Gross, R. (author), Goennenwein, S.T.B. (author), Kläui, M. (author)Magnons are the elementary excitations of a magnetically ordered system. In ferromagnets, only a single band of low-energy magnons needs to be considered, but in ferrimagnets the situation is more complex owing to different magnetic sublattices involved. In this case, low lying optical modes exist that can affect the dynamical response. Here we...journal article 2016
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Aqeel, A. (author), Vlietstra, N. (author), Heuver, J.A. (author), Bauer, G.E.W. (author), Noheda, B. (author), Van Wees, B.J. (author), Palstra, T.T.M. (author)We report on the spin-Hall magnetoresistance (SMR) and spin Seebeck effect (SSE) in multiferroic CoCr2O4 (CCO) spinel thin films with Pt contacts. We observe a large enhancement of both signals below the spin-spiral (Ts=28K) and the spin lock-in (Tlock?in=14K) transitions. The SMR and SSE responses in the spin lock-in phase are one order of...journal article 2015
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Schreier, M. (author), Chiba, T. (author), Niedermayr, A. (author), Lotze, J. (author), Huebl, H. (author), Geprags, S. (author), Takahashi, S. (author), Bauer, G.E.W. (author), Gross, R. (author), Goennenwein, S.T.B. (author)We report the observation of current-induced spin torque resonance in yttrium iron garnet/platinum bilayers. An alternating charge current at GHz frequencies in the platinum gives rise to dc spin pumping and spin Hall magnetoresistance rectification voltages, induced by the Oersted fields of the ac current and the spin Hall effect-mediated spin...journal article 2015
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Rameshti, B.Z. (author), Cao, Y. (author), Bauer, G.E.W. (author)We apply Mie scattering theory to study the interaction of magnetic spheres with microwaves in cavities beyond the magnetostatic and rotating wave approximations. We demonstrate that both strong and ultrastrong coupling can be realized for stand alone magnetic spheres made from yttrium iron garnet (YIG), acting as an efficient microwave antenna....journal article 2015
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Cao, Y. (author), Yan, P. (author), Huebl, H. (author), Goennenwein, S.T.B. (author), Bauer, G.E.W. (author)We formulate a scattering theory to study magnetic films in microwave cavities beyond the independent-spin and rotating-wave approximations of the Tavis-Cummings model. We demonstrate that strong coupling can be realized not only for the ferromagnetic resonance mode, but also for spin-wave resonances; the coupling strengths are mode dependent...journal article 2015
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Kamra, A. (author), Keshtgar, H. (author), Yan, P. (author), Bauer, G.E.W. (author)We model the injection of elastic waves into a ferromagnetic film (F) by a nonmagnetic transducer (N). We compare the configurations in which the magnetization is normal and parallel to the wave propagation. The lack of axial symmetry in the former results in the emergence of evanescent interface states. We compute the energy-flux transmission...journal article 2015
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Chiba, T. (author), Schreier, M. (author), Bauer, G.E.W. (author), Takahashi, S. (author)The spin-torque ferromagnetic resonance (ST-FMR) in a bilayer system consisting of a magnetic insulator such as Y3Fe5O12 and a normal metal with spin-orbit interaction such as Pt is addressed theoretically. We model the ST-FMR for all magnetization directions and in the presence of fieldlike spin-orbit torques based on the drift-diffusion spin...journal article 2015
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Kamra, A. (author), Witek, F.P. (author), Meyer, S. (author), Huebl, H. (author), Geprägs, S. (author), Gross, R. (author), Bauer, G.E.W. (author), Goennenwein, S.T.B. (author)We measure the low-frequency thermal fluctuations of pure spin current in a platinum film deposited on yttrium iron garnet via the inverse spin Hall effect (ISHE)-mediated voltage noise as a function of the angle ? between the magnetization and the transport direction. The results are consistent with the fluctuation-dissipation theorem in terms...journal article 2014
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Wang, S.Z. (author), Xia, K. (author), Bauer, G.E.W. (author)We compute the thermoelectric transport parameterized by the Seebeck coefficient and thermal/electric conductance of random-alloy FeCo/MgO/FeCo(001) magnetic tunnel junctions (MTJs) from first principles using a generalized Landauer-Büttiker formalism. The thermopower is found to be typically smaller than those of Fe/MgO/Fe(001) MTJs. The ...journal article 2014
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Joibari, F.K. (author), Blanter, Y.M. (author), Bauer, G.E.W. (author)Nonresonant circularly polarized electromagnetic radiation can exert torques on magnetizations by the inverse Faraday effect (IFE). Here, we discuss the enhancement of IFE by spin-orbit interactions. We illustrate the principle by studying a simple generic model system, i.e., the quasi-one-dimensional ring in the presence of linear/cubic Rashba...journal article 2014
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Chiba, T. (author), Bauer, G.E.W. (author), Takahashi, S. (author)We formulate a theory of the ac spin Hall magnetoresistance in a bilayer system consisting of a magnetic insulator such as yttrium iron garnet and a heavy metal such as platinum. We derive expressions for the dc voltage generation based on the drift-diffusion spin model and quantum mechanical boundary condition at the interface that reveal a...journal article 2014
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Skarsvag, H. (author), Bauer, G.E.W. (author), Brataas, A. (author)We study the dynamics of spin valves consisting of two layers of magnetic insulators separated by a normal metal in the macrospin model. A current through the spacer generates a spin Hall current that can actuate the magnetization via the spin-transfer torque. We derive expressions for the effective Gilbert damping and the critical currents for...journal article 2014