Fig. 1: Crystal and electronic structure of EuSn2(As,P)2 and RA-SHG patterns.
From: Quantum decoherence by magnetic fluctuations in a magnetic topological insulator
a Crystal structure showing half of the conventional magnetic unit cell. Red arrows depict Eu2+ local magnetic moments, which lie within the plane along the a axis. Moments are aligned within each plane and antialigned with neighboring planes, forming long-range A-type antiferromagnetism. The inset illustrates the local environment surrounding the Eu2+ ions, showing D3d site symmetry. b Orbital-resolved electronic band structure of EuSn2As2 from DFT. Vertical arrows highlight optical transitions near the M point contributing to near-resonant SHG. The irreducible representations of the states participating in the resonances are labeled. The right inset shows an energy level diagram of MD-SHG involving both ED and MD optical transitions. c Parallel polarization RA-SHG patterns for all three materials at 50 K. The top left panel defines the oblique-incidence scattering geometry. The top row shows Sin-Sout (SS) polarization patterns and the bottom row shows Pin-Pout (PP) polarization patterns.
