1 research outputs found
Extrinsic Nonlinear Kerr Rotation in Topological Materials under a Magnetic Field
Topological properties in quantum materials are often
governed
by symmetry and tuned by crystal structure and external fields, and
hence, symmetry-sensitive nonlinear optical measurements in a magnetic
field are a valuable probe. Here, we report nonlinear magneto-optical
second harmonic generation (SHG) studies of nonmagnetic topological
materials including bilayer WTe2, monolayer WSe2, and bulk TaAs. The polarization-resolved patterns of optical SHG
under a magnetic field show nonlinear Kerr rotation in these time-reversal
symmetric materials. For materials with 3-fold rotational symmetric
lattice structure, the SHG polarization pattern rotates just slightly
in a magnetic field, whereas in those with mirror or 2-fold rotational
symmetry, the SHG polarization pattern rotates greatly and distorts.
These different magneto-SHG characters can be understood by considering
the superposition of the magnetic field-induced time-noninvariant
nonlinear optical tensor and the crystal-structure-based time-invariant
counterpart. The situation is further clarified by scrutinizing the
Faraday rotation, whose subtle interplay with crystal symmetry accounts
for the diverse behavior of the extrinsic nonlinear Kerr rotation
in different materials. Our work illustrates the application of magneto-SHG
techniques to directly probe nontrivial topological properties, and
underlines the importance of minimizing extrinsic nonlinear Kerr rotation
in polarization-resolved magneto-optical studies