Multi-probe, laser-scanning optical microscopy for investigation of novel magnetic domain structures and boundaries

Spin ordering in a magnetic material leads to the breaking of time-reversal symmetry along with some crystallographic symmetries, defining the magnetic symmetry group of the magnetic phase. Multiple degenerate ground states always exist, related through these broken symmetries, leading to interesting magnetic domain structures in macroscopic samples, which potentially host novel low-dimensional phases at the domain boundaries. In this talk, I will present our development of a spatially resolved, diffraction limited, ultrafast laser-based optical scanning microscope, which includes measurement capabilities of the magneto-optic Kerr effect (MOKE), a direct measure of broken time-reversal symmetry, and the optical second harmonic generation rotational anisotropy (SHG RA), a sensitive probe to broken spatial symmetries. I will present a comparison between this scanning-based microscope and a more traditional wide-field microscope. I will then discuss our experimental results on resolving magnetic domain structures in two types of antiferromagnetism, Ising and Heisenberg, on a honeycomb and a triangle lattice respectively. Finally, I will discuss the possibility of incorporating time-resolution into the aforementioned static probes.