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Contains fulltext : 286742.pdf (Publisher’s version ) (Open Access)

The quadratic electro-optic effect (Kerr effect) is shown to be efficiently induced by a terahertz (THz) electric field in the quasi-two-dimensional (2D) material MnPS3. The waveform of the THz-induced response practically follows the intensity of the employed nearly single-cycle THz pulse. While neither THz-induced absorption nor the linear electro-optical effect are observed, we demonstrate that the THz electric field induces the refraction coefficient anisotropy experienced by light at the wavelength of 800 nm. In our experiment, the anisotropy results in polarization rotation of the light and corresponds to a nonlinear refractive index of the sample of approximately 13.1 × 10−14 W−1 cm2. This promotes the quasi-2D MnPS3 as a promising candidate for practical application in future ultrafast electro-optical devices.

Coupling up of spins and lattice The development of spintronics and magnetic data storage relies on understanding and controlling the dynamics of magnetic excitations within a material. Of crucial importance for practical applications is how fast the magnetization can be switched. Mashkovich et al . report the use of ultrafast terahertz radiation to create magnon excitations in the antiferromagnet cobalt difluoride that can then be coupled with phonon excitations (see the Perspective by Juraschek and Narang). Using light to control coupling between the spins and the lattice provides a route to manipulate magnetization in antiferromagnetic materials on ultrafast time scales. —ISO