Abstract-Using ultrashort terahertz pulses to directly probe spin dynamics in insulating antiferromagnets

Pamela Bowlan, S A Trugman, Dzmitry Yarotski, Antoinette J Taylor, Rohit P Prasankuma

http://iopscience.iop.org/article/10.1088/1361-6463/aab8da

Terahertz pulses are a direct and general probe of ultrafast spin dynamics in insulating antiferromagnets (AFM). This is shown by using optical-pump, THz-probe spectroscopy to directly track AFM spin dynamics in the hexagonal multiferroic HoMnO3 and the orthorhombic multiferroic TbMnO3. Our studies show that despite the different structural and spin orders in these materials, THz pulses can unambiguously resolve spin dynamics after optical photoexcitation. We believe that this approach is quite general and can be applied to a broad range of materials with different AFM spin alignments, providing a novel non-contact approach for probing AFM order with femtosecond temporal resolution.

Abstract-Nonlinear high-temperature superconducting terahertz metamaterials

Nathaniel K Grady¹, Bradford G Perkins Jr^2,3, Harold Y Hwang², Nathaniel C Brandt², Darius Torchinsky², Ranjan Singh¹, Li Yan¹, Daniel Trugman¹, Stuart A Trugman¹, Q X Jia¹, Antoinette J Taylor¹, Keith A Nelson² and Hou-Tong Chen^1,4

http://iopscience.iop.org/1367-2630/15/10/105016

We report the observation of a nonlinear terahertz response of split-ring resonator arrays made of high-temperature superconducting films. Intensity-dependent transmission measurements indicate that the resonance strength decreases dramatically (i.e. transient bleaching) and the resonance frequency shifts as the intensity is increased. Pump–probe measurements confirm this behaviour and reveal dynamics on the few-picosecond timescale.