Regensburg 2022 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Ultra-Fast Phenomena

HL 13.7: Talk

Tuesday, September 6, 2022, 11:15–11:30, H33

Intense terahertz radiation via the transverse thermoelectric effect — •Tim Priessnitz^1,2, Petar Yordanov¹, Min-Jae Kim^1,2,3, Georg Cristiani¹, Gennady Logvenov¹, Bernhard Keimer¹, and Stefan Kaiser^1,2,3 — ¹Max-Planck Institute for Solid State Research, 70569 Stuttgart, Germany — ²4th Physics Institute and Research Center SCoPE, University of Stuttgart, 70569 Stuttgart, Germany — ³Institute of Solid State and Materials Physics, Technical University Dresden, 01069 Dresden, Germany

Terahertz (THz) radiation became a powerful tool with widespread applications ranging from imaging and spectroscopy to nonlinear optical control of materials. However, efficient and scalable THz sources remain rare. Here, we present a novel approach to generate powerful THz radiation making use of an ultrafast current induced via the transverse thermoelectric effect (TTE). We realize this in off-cut grown thin films of the delafossite PdCoO₂ and the cuprate La_1.84Sr_0.16CuO₄ driven by femtosecond laser pulses resulting in an ultrafast transient diffusion of charge carriers. Characterizing the resulting THz radiation, we find it comparable in power and spectral bandwidth to standard emitters based on nonlinear crystals. A first basic model including the Seebeck anisotropy, electrical and thermal conductivities and the transient diffusivity allows materials based predictions. Due to its simplicity and potential for scalability in terms of multiple tunable material parameters, THz generation based on the TTE opens a new avenue for high-field THz generation and novel cost-efficient emitters.