ABSTRACT
We report the picosecond spin current generation from the interface between a heavy metal and a vicinal antiferromagnet insulator Cr_{2}O_{3} by laser pulses at room temperature and zero magnetic field. It is converted into a detectable terahertz emission in the heavy metal via the inverse spin Hall effect. The vicinal interfaces are apparently the source of the picosecond spin current, as evidenced by the proportional terahertz signals to the vicinal angle. We attribute the origin of the spin current to the transient magnetic moment generated by an interfacial nonlinear magnetic-dipole difference-frequency generation. We propose a model based on the in-plane inversion symmetry breaking to quantitatively explain the terahertz intensity with respect to the angles of the laser polarization and the film azimuth. Our work opens new opportunities in antiferromagnetic and ultrafast spintronics by considering symmetry breaking.
ABSTRACT
Nanoscale refractive index (RI) sensors based on plasmonic structures usually suffer from a low figure of merit (FoM) due to the broad linewidth of the resonance peaks. Here, we report a magnetoplasmon-based RI sensing method with high FoM in the designed H-shaped magnetoplasmonic crystals. Instead of the light intensity spectrum, the Faraday signal is detected to analyze the changes of the surrounding RI. Sharp resonance with extremely narrow linewidth is obtained by plotting the reciprocal Faraday rotation near the null point region. Therefore, the FoM is hugely enhanced, and a theoretical value exceeding 1775/RIU is achieved, which is one order of magnitude higher than has ever been reported, to the best of our knowledge, for the RI sensor based on the Faraday effect. The Faraday reversal and the enhanced FoM arise from the Fano resonance. These findings are of potential value for practical high performance biochemical sensors.
ABSTRACT
The magneto-optical Kerr effect, especially the Kerr slope, is of great significance to magneto-optical devices. Herein, we developed a method to tune the magneto-optical effect by the nanograting cross section. Both the simulation and experiment confirm that the resonance strength of the plasmon can be modulated by the nanograting cross section, resulting in the large Kerr slope and Kerr rotation. By designing the nanograting cross section, we obtained the Kerr slope of 0.397°/nm, which is 4 orders of magnitude higher than the reported results. And the Kerr rotation of the magnetic nanograting reaches up to 1.218°, which is 24 times higher than the flat Co film. Such a huge enhancement on the Kerr slope and the Kerr rotation may have profound applications in magneto-optical devices in the future.
