Please use this identifier to cite or link to this item: http://dx.doi.org/10.14279/depositonce-10076
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Main Title: Terahertz magnetic field enhancement in an asymmetric spiral metamaterial
Author(s): Polley, Debanjan
Hagström, Nanna Zhou
Korff Schmising, Clemens von
Eisebitt, Stefan
Bonetti, Stefano
Type: Article
Language Code: en
Abstract: We use finite element simulations in both the frequency and the time-domain to study the terahertz resonance characteristics of a metamaterial (MM) comprising a spiral connected to a straight arm. The MM acts as a RLC circuit whose resonance frequency can be precisely tuned by varying the characteristic geometrical parameters of the spiral: inner and outer radius, width and number of turns. We provide a simple analytical model that uses these geometrical parameters as input to give accurate estimates of the resonance frequency. Finite element simulations show that linearly polarized terahertz radiation efficiently couples to the MM thanks to the straight arm, inducing a current in the spiral, which in turn induces a resonant magnetic field enhancement at the center of the spiral. We observe a large (approximately 20 times) and uniform (over an area of $\sim 10~\mu m^{2}$) enhancement of the magnetic field for narrowband terahertz radiation with frequency matching the resonance frequency of the MM. When a broadband, single-cycle terahertz pulse propagates towards the metamaterial, the peak magnetic field of the resulting band-passed waveform still maintains a 6-fold enhancement compared to the peak impinging field. Using existing laser-based terahertz sources, our metamaterial design allows to generate magnetic fields of the order of 2 T over a time scale of several picoseconds, enabling the investigation of non-linear ultrafast spin dynamics in table-top experiments. Furthermore, our MM can be implemented to generate intense near-field narrowband, multi-cycle electromagnetic fields to study generic ultrafast resonant terahertz dynamics in condensed matter.
URI: https://depositonce.tu-berlin.de/handle/11303/11185
http://dx.doi.org/10.14279/depositonce-10076
Issue Date: 2018
Date Available: 20-May-2020
DDC Class: 530 Physik
Subject(s): terahertz
magnetic field
metamaterials
Sponsor/Funder: EC/H2020/715452/EU/Understanding the speed limits of magnetism/MAGNETIC-SPEED-LIMIT
License: https://creativecommons.org/licenses/by/3.0/
Journal Title: Journal of Physics B: Atomic, Molecular and Optical Physics
Publisher: IOP Publishing
Publisher Place: Bristol
Volume: 51
Issue: 22
Article Number: 224001
Publisher DOI: 10.1088/1361-6455/aae579
EISSN: 1361-6455
ISSN: 0953-4075
Appears in Collections:FG Röntgenoptik und Nanometer-Optik » Publications

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