Oblique-incidence Sagnac interferometric scanning microscope for studying magneto-optic effects of materials at low temperatures

We describe an oblique-incidence zero-area Sagnac interferometric microscope for studying spatial and temperature dependence of magneto-optic (MO) effects in samples under cryogenic conditions. The microscope is capable of independently measuring Kerr effects from three Cartesian components of a magnetization and thus can be used to map out the magnetization vector across the sample. For illustration, we present MO Kerr effect images of magnetic domains at 77 K of a LaCrGe3 crystal terminated with an a-c plane (the plane that contains the lattice a-axis and c-axis). We further present measurements of magnetization in these domains from 90 to 77 K during zero-field cooling and field cooling in an external magnetic field from 20 to 150 Oe. The inherently high sensitivity and the capability of detecting a magnetization without external modulation makes such a Sagnac interferometric microscope particularly useful for studying magnetic effects in novel materials at low temperatures.

Automated summary

The oblique-incidence zero-area Sagnac interferometric microscope has the ability to independently measure the three Cartesian components of magnetization, making it useful for studying magnetic effects at low temperatures. Observing magnetic domains of LaCrGe3 crystal demonstrates the MO Kerr effect at different temperatures.