Please use this identifier to cite or link to this item: http://dx.doi.org/10.14279/depositonce-10076
 Main Title: Terahertz magnetic field enhancement in an asymmetric spiral metamaterial Author(s): Polley, DebanjanHagström, Nanna ZhouKorff Schmising, Clemens vonEisebitt, StefanBonetti, 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/11303/11185http://dx.doi.org/10.14279/depositonce-10076 Issue Date: 2018 Date Available: 20-May-2020 DDC Class: 530 Physik Subject(s): terahertzmagnetic fieldmetamaterials 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