Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 59: Plasmonics and Nanooptics

O 59.15: Poster

Dienstag, 21. März 2017, 18:30–20:30, P2-OG1

Low-temperature scattering-type scanning near-field optical microscopy — •Denny Lang^1,2, Jonathan Döring², Susanne C. Kehr², Lukas M. Eng², Stephan Winnerl¹, Harald Schneider¹, and Manfred Helm^1,2 — ¹HZDR, 01328 Dresden, Germany. — ²IAP, TU Dresden, 01062 Dresden, Germany.

We present a combination of a versatile low-temperature scattering-type near-field optical microscope (LT-s- SNOM [1]) with a tunable infrared free-electron laser (FEL [2]). Our s-SNOM operates over a broad temperature range from 15 - 300 K [1,3,4] and is unique in being tunable over a broad frequency range, thanks to the FEL. The overall LT-s-SNOM functionality down to lowest temperature was tested on both standard Au and structured Si-SiO₂ samples, revealing net near-field contrasts and no topography cross-talk. Secondly, we investigated several ferroelectric phase transitions in barium titanate single crystals at 273 K [1] and 193 K [5], allowing to associate clear near-field resonances to every phase and each ferroelectric domain; here, the clear benefit of our LT-s- SNOM pays off, being able to record s-SNOM, PFM, KPFM and topographic data with one and the same tip from every sample surface spot. Thirdly, we used these piezoelectrics to quantify the local temperature increase under the AFM tip upon IR irradiation. [1] Döring et al., Appl. Phys. Lett. 105, 053109 (2014). [2] Kuschewski et al., Appl. Phys. Lett. 108, 113102 (2016). [3] Yang et al., Rev. Sci. Instrum. 84, 023701 (2013). [4] McLeod et al., Nature Phys. (2016); DOI: 10.1038/NPHYS3882. [5] Döring et al., J. Appl. Phys. 120, 084103 (2016).