We investigated laser-pulse-induced terahertz (THz) emission in Ta/CoFeB/Ir/CoFeB/Ta layered synthetic magnets with different Ir spacer thicknesses. THz emissions were observed under no applied magnetic fields for samples exhibiting interlayer antiferromagnetic exchange couplings, and those THz emissions also showed oscillatory behavior against the Ir spacer thicknesses. These results are qualitatively explained with the THz emission mechanism due to the inverse spin Hall effect for the laser-induced spin current in the layered structures. We also discuss the effect of a non-collinear configuration of magnetizations on THz emission with macrospin simulation.

Mobile phone technology has led to implementation of portable and inexpensive microscopes. Lightemitting diode (LED) array microscopes support various multicontrast imaging by flexible illumination patterns of the LED array that can be achieved without changing the optical components of the microscope. Here, we demonstrate a mobile-phone-based LED array microscope to realize multimodal imaging with bright-field, dark-field, differential phase-contrast, and Rheinberg illuminations using as few as 37 LED bulbs. Using this microscope, we obtained high-contrast images of living cells. Furthermore, by changing the color combinations of Rheinberg illumination, we were able to obtain images of living chromatic structures with enhanced or diminished contrast. This technique is expected to be a foundation for high-contrast microscopy used in modern field studies. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.