200 research outputs found
Reconfigurable quantum metamaterials
By coupling controllable quantum systems into larger structures we introduce
the concept of a quantum metamaterial. Conventional meta-materials represent
one of the most important frontiers in optical design, with applications in
diverse fields ranging from medicine to aerospace. Up until now however,
metamaterials have themselves been classical structures and interact only with
the classical properties of light. Here we describe a class of dynamic
metamaterials, based on the quantum properties of coupled atom-cavity arrays,
which are intrinsically lossless, reconfigurable, and operate fundamentally at
the quantum level. We show how this new class of metamaterial could be used to
create a reconfigurable quantum superlens possessing a negative index gradient
for single photon imaging. With the inherent features of quantum superposition
and entanglement of metamaterial properties, this new class of dynamic quantum
metamaterial, opens a new vista for quantum science and technology.Comment: 16 pages, 8 figure
Tailoring interfacial effect in multilayers with Dzyaloshinskii-Moriya interaction by helium ion irradiation
We show a method to control magnetic interfacial effects in multilayers with Dzyaloshinskii–Moriya interaction (DMI) using helium (He+) ion irradiation. We report results from SQUID magnetometry, ferromagnetic resonance as well as Brillouin light scattering results on multilayers with DMI as a function of irradiation fluence to study the effect of irradiation on the magnetic properties of the multilayers. Our results show clear evidence of the He+irradiation effects on the magnetic properties which is consistent with interface modification due to the effects of the He+ irradiation. This external degree of freedom offers promising perspectives to further improve the control of magnetic skyrmions in multilayers, that could push them towards integration in future technologies
Green's function for metamaterial superlens: Evanescent wave in the image
We develop a new method to calculate the evanescent wave, the subdivided
evanescent waves (SEWs), and the radiative wave, which can be obtained by
separating the global field of the image of metamaterial superlens. The method
is based on Green's function, and it can be applied in other linear systems.
This study could help us to investigate the effect of evanescent wave on
metamaterial superlens directly, and give us a new way to design new devices.Comment: 15 pages, 3 figure
Controlling spin pumping into superconducting Nb by proximity-induced spin-triplet Cooper pairs
Proximity-induced long-range spin-triplet supercurrents, important for the field of superconducting spintronics, are generated in superconducting/ferromagnetic heterostructures when interfacial magnetic inhomogeneities responsible for spin mixing and spin flip scattering are present. The multilayer stack Nb/Cr/Fe/Cr/Nb has been shown to support such currents when fabricated into Josephson junction devices. However, creating pure spin currents controllably in superconductors outside of the Josephson junction architecture is a bottleneck to progress. Recently, ferromagnetic resonance was proposed as a possible direction, the signature of pure supercurrent creation being an enhancement of the Gilbert damping below the superconducting critical temperature, but the necessary conditions are still poorly established. Here, we demonstrate that pumping pure spin currents into a superconductor in the presence of an external magnetic field is only possible when conditions supporting proximity-induced spin-triplet effects are satisfied. Our study is an important step forward for pure spin supercurrent creation, considerably advancing the field of superconducting spintronics
Emergent Phenomena Induced by Spin-Orbit Coupling at Surfaces and Interfaces
Spin-orbit coupling (SOC) describes the relativistic interaction between the
spin and momentum degrees of freedom of electrons, and is central to the rich
phenomena observed in condensed matter systems. In recent years, new phases of
matter have emerged from the interplay between SOC and low dimensionality, such
as chiral spin textures and spin-polarized surface and interface states. These
low-dimensional SOC-based realizations are typically robust and can be
exploited at room temperature. Here we discuss SOC as a means of producing such
fundamentally new physical phenomena in thin films and heterostructures. We put
into context the technological promise of these material classes for developing
spin-based device applications at room temperature
Near-field magneto-caloritronic nanoscopy on ferromagnetic nanostructures
Near-field optical microscopy by means of infrared photocurrent mapping has rapidly developed in recent years. In this letter we introduce a near-field
induced contrast mechanism arising when a conducting surface, exhibiting a
magnetic moment, is exposed to a nanoscale heat source. The
magneto-caloritronic response of the sample to near-field excitation of a
localized thermal gradient leads to a contrast determined by the local state of magnetization. By comparing the measured electric response of a magnetic reference sample with numerical simulations we derive an estimate of the field enhancement and the corresponding temperature profile induced on the sample surface.This work was supported by the Deutsche Forschungsgemeinschaft through grant HE 2063/5-1 to JH. The work also received funding from the ERC synergy grant No. 61011
A parametric study of the lensing properties of dodecagonal photonic quasicrystals
We present a study of the lensing properties of two-dimensional (2-D)
photonic quasicrystal (PQC) slabs made of dielectric cylinders arranged
according to a 12-fold-symmetric square-triangle aperiodic tiling. Our
full-wave numerical analysis confirms the results recently emerged in the
technical literature and, in particular, the possibility of achieving focusing
effects within several frequency regions. However, contrary to the original
interpretation, such focusing effects turn out to be critically associated to
local symmetry points in the PQC slab, and strongly dependent on its thickness
and termination. Nevertheless, our study reveals the presence of some peculiar
properties, like the ability to focus the light even for slabs with a reduced
lateral width, or beaming effects, which render PQC slabs potentially
interesting and worth of deeper investigation. Key words: Photonic
quasicrystals; negative refraction; superlensing.Comment: 12 pages, 8 figures, to be pubblished in Photonics and Nanostructures
- Fundamentals and Application
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