Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of giant surface second harmonic generation coupled to
  nematic orders in the van der Waals antiferromagnet FePS$_3$   Second harmonic generation has been applied to study lattice, electronic and
magnetic proprieties in atomically thin materials. However, inversion symmetry
breaking is usually required for the materials to generate a large signal. In
this work, we report a giant second-harmonic generation that arises below the
N\'eel temperature in few-layer centrosymmetric FePS$_3$. Layer-dependent study
indicates the detected signal is from the second-order nonlinearity of the
surface. The magnetism-induced surface second-harmonic response is two orders
of magnitude larger than those reported in other magnetic systems, with the
surface nonlinear susceptibility reaching 0.08--0.13 nm$^2$/V in 2 L--5 L
samples. By combing linear dichroism and second harmonic generation
experiments, we further confirm the giant second-harmonic generation is coupled
to nematic orders formed by the three possible Zigzag antiferromagnetic
domains. Our study shows that the surface second-harmonic generation is also a
sensitive tool to study antiferromagnetic states in centrosymmetric atomically
thin materials.

29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat