5 research outputs found
Broadband enhancement of the magneto-optical activity of hybrid Au loaded Bi:YIG
We unravel the underlying near-field mechanism of the enhancement of the
magneto-optical activity of bismuth-substituted yttrium iron garnet films
(Bi:YIG) loaded with gold nanoparticles. The experimental results show that the
embedded gold nanoparticles lead to a broadband enhancement of the
magneto-optical activity with respect to the activity of the bare Bi:YIG films.
Full vectorial near- and far-field simulations demonstrate that this broadband
enhancement is the result of a magneto-optically enabled cross-talking of
orthogonal localized plasmon resonances. Our results pave the way to the
on-demand design of the magneto-optical properties of hybrid magneto-plasmonic
circuitry.Comment: 6 Pages, 3 Figure
Giant confinement of excited surface electrons in a two-dimensional metal-organic porous network
Two-dimensional metal-organic porous networks (2D-MOPNs) are highly ordered
quantum boxes for exploring surface confinements. In this context, the electron
confinement from occupied Shockley-type surface states (SS) has been vigorously
studied in 2D-MOPNs. In contrast, the confinement of excited surface states,
such as image potential states (IPSs), remains elusive. In this work, we apply
two-photon photoemission to investigate the confinement exemplarily for the
first image state in a Cu-coordinated T4PT porous network (Cu-T4PT). Due to the
lateral potential confinement in the Cu-T4PT, periodic replicas of the IPS as
well as the SS are present in a momentum map. Surprisingly, the first IPS
transforms into a nearly flat band with a substantial increase of the effective
mass (> 150 %), while the band dispersion of the SS is almost unchanged. The
giant confinement effect of the excited electrons can be attributed to the
wavefunction location of the first IPS perpendicular to the surface, where the
majority probability density mainly resides at the same height as repulsive
potentials formed by the Cu-T4PT network. This coincidence leads to a more
effective scattering barrier to the IPS electrons, which is not observed in the
SS. Our findings demonstrate that the vertical potential landscape in a porous
architecture also plays a crucial role in surface electron confinement
Temperature-driven confinements of surface electrons and adatoms in a weakly interacting 2D organic porous network
Two-dimensional organic porous networks (2DOPNs) have opened new vistas for
tailoring the physicochemical characteristics of metallic surfaces. These
typically chemically bound nanoporous structures act as periodical quantum
wells leading to the 2D confinements of surface electron gases, adatoms and
molecular guests. Here we propose a new type of porous network with weakly
interacting 2,4,6-triphenyl-1,3,5-triazine (TPT) molecules on a Cu(111)
surface, in which a temperature-driven (T-driven) phase transition can
reversibly alter the supramolecular structures from a close-packed (CP-TPT)
phase to a porous-network (PN-TPT) phase. Crucially, only the low-temperature
PN-TPT exhibits subnano-scale cavities that can confine the surface state
electrons and metal adatoms. The confined surface electrons undergo a
significant electronic band renormalization. To activate the spin degree of
freedom, the T-driven PN-TPT structure can additionally trap Co atoms within
the cavities, forming highly ordered quantum dots. Our theoretical simulation
reveals a complex spin carrier transfer from the confined Co cluster to the
neighbouring TPT molecules via the underlying substrate. Our results
demonstrate that weakly interacting 2DOPN offers a unique quantum switch
capable of steering and controlling electrons and spin at surfaces via tailored
quantum confinements
Plasmonic wavelength-dependent optical switch
Kilbane D, Prinz E, Eul T, et al. Plasmonic wavelength-dependent optical switch. Optics Express. 2023;31(6):9579-9590.We design and experimentally demonstrate an optical switch based on the interference of plasmonic modes in whispering gallery mode (WGM) antennas. Simultaneous excitation of even and odd WGM modes, enabled by a small symmetry breaking via non-normal illumination, allows switching the plasmonic near field between opposite sides of the antenna, depending on the excitation wavelength used in a wavelength range of 60 nm centered around 790 nm. This proposed switching mechanism is experimentally demonstrated by combining photoemission electron microscopy (PEEM) with a tunable wavelength femtosecond laser source in the visible and infrared