Speaker
Description
Terahertz (THz) electromagnetic fields are highly interesting to probe and even drive fundamental ultrafast modes in spintronic nanostructures. Examples include magnons, phonons and spin-polarized electron transport. Here, we demonstrate how free-space THz electric (rather than magnetic) fields can be used to exert torque on the magnetic order parameter (the Neel vector) in the novel antiferro-magnet Mn2Au. Instead of slow electrical probing of the state of the sample through anisotropic magnetoresistance [2], we make use of ultrafast magneto-optic probing to trace the pump-induced spin dynamics. We find that the THz electric field rotates the Neel vector by up to 30°, followed by a strongly damped magnon oscillation at 0.6 THz. Simulations indicate that coherent switching of the Neel vector by 90°, which is a central goal of antiferromagnetic spintronics, is in close reach.
Second, to develop a new source of intense broadband THz pulses, we significantly improved the performance of the recently developed spintronic THz emitters (STEs) [3]. By optimized management of optical pump and emitted THz light and the heat flow, we achieve peak THz electric fields above 1.5 MV/cm, a fluence above 1 mJ/cm2 with a spectrum fully covering the range 0.1-12 THz. These values make the STE output comparable to state-of-the-art LiNbO3 THz sources in terms of field strength and fluence, while its bandwidth, easy polarization control and alignment make the STE an attractive and complementary alternative for nonlinear THz spectroscopy. Finally, we use the STE to generate pairs of THz pulses with variable delay. We show that these THz double-pulses allow us to spectrally resolve the image of the THz beam as measured with a conventional THz camera.
References
[1] A.L. Chekhov et al., Phys. Rev. X 11, 041055 (2021).
[2] J.J.F. Heitz et al., Phys. Rev. Appl. 16, 064047 (2021).
[3] T. Seifert et al., Appl. Phys. Lett. 120, 180401 (2022).
| Abstract Number (department-wise) | PC 08 |
|---|---|
| Department | PC (Wolf) |
