THz control of magnetism with metamaterials (Conference Presentation)

Abstract

Understanding how spins move at pico- and femtosecond time scales is the focus of much of contemporary research in magnetism. I will go through some basic and more advanced concepts in the exciting emerging field of terahertz (THz) magnetism, where electromagnetic radiation in the 0.1-10 THz range, the so-called THz gap, is used to probe or to control spin dynamics at these time scales. I will give an overview of the current research in THz magnetism. As illustrating examples, I will briefly discuss how low-intensity THz radiation can be used to probe the fundamentals of spin- dependent transport in the linear regime [1]. I will then describe how intense THz fields can be used to drive coherent and incoherent ultrafast spin dynamics in nonlinear regimes, both with broadband [2] and narrowband radiation [3]. Finally, I will show some recent implementation of metamaterials [4] aimed at selectively enhancing the terahertz magnetic field in the near-field [5]. I will also illustrate the design of an anti-reflection coating that allows for table-top, femtosecond pump-probe experiments in generic nanostructures surrounded by highly reflective metamaterials [6]. [1] Z. Jin et al., Nature Physics 11, 761 (2015) [2] S. Bonetti et al, Physical Review Letters 117, 087205 (2016) [3] Z. Wang et al., Selective THz control of magnetic order: new opportunities from superradiant undulator sources, Journal of Physics D: Applied Physics, in press (2018) [4] Hou-Tong Chen et al., Terahertz Science and Technology 1, 42 (2008) [5] D. Polley, et al. Journal of Physics D: Applied Physics 51, 084001 (2018) [6] M. Pancaldi et al. Optics Letters 26, 2917 (2018)