XXXVII International Symposium on Dynamical Properties of Solids (DyProSo2019)

Near-field THz nanoscopy with novel accelerator-based photon sources

10 Sept 2019, 11:10

30m

Keynote Keynote talk

Speaker

Lukas M. Eng (Institute of Applied Physics, School of Science, TU Dresden, 01062 Dresden, Germany)

Description

This talk advertises scattering-type scanning near-field infrared nanospectroscopy (s-SNIM) in the spectral range of 75 to 1.2 THz [1,2], as provided by the free-electron laser FELBE at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Germany. By combining s-SNIM with FELBE, we demonstrate a -independent optical resolution of ~10 nm only, by exploring structured Au samples, Graphene-nanotransistors, meta-materials [3,4], and local-scale ferroic phase-transitions [5 - 7] down to LHe temperatures [8]. Moreover, also the non-linear optical responses at IR wavelengths can be explored as recently demonstrated when inspecting highly-doped GaAs/InGaAs core/shell nanowires [9]. Our THz-s-SNIM was also integrated into a THz pump-probe setup for the local analysis of excited states in structured SiGe samples. We developed a sophisticated demodulation technique that extracts pump-induced signals with a superior signal-to-noise ratio [10]. In addition, HZDR recently extended the available wave¬length ranges down to the 100 GHz radiation, employing the novel super-radiant TELBE light source [11,12]. We adapted our s-SNIM to that novel TELBE photon source as well, achieving an equally high spatial resolution as with FELBE. This allows now to bridge the famous THz-gap in order to explore novel quantum phenomena of magnons, spins, and phonon polaritons.
References:
[1] F. Kuschewski et al., Appl. Phys. Lett. 108, 113102 (2016).
[2] S.C. Kehr et al., Synch. Rad. News 30, 31 (2017).
[3] S.C. Kehr et al., ACS Photonics 3, 20 (2016).
[4] M. Fehrenbacher et al., Nano Lett. 15, 1057 (2015).
[5] J. Döring et al., J. Appl. Phys. 120, 084103 (2016).
[6] J. Döring, LME, et al., Appl. Phys. Lett. 105 , 053109 (2014).
[7] A. Butykai, LME, et al., Sci. Rep. 7, 44663 (2017).
[8] D. Lang, LME, et al., Rev. Sci. Instrum. 89, 033702 (2018).
[9] D. Lang, LME, et al., Nanotechnology 30, 084003 (2019).
[10] F. Kuschewski, LME, et al., Sci. Rep. 5, 12582 (2015).
[11] B. Green et al., Sci. Rep. 6, 22256 (2016).
[12] S. Kovalev et al., Struct. Dyn. 4, 024301 (2017).