Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Large magneto-optical Kerr effect and imaging of magnetic octupole
  domains in an antiferromagnetic metal   When a polarized light beam is incident upon the surface of a magnetic
material, the reflected light undergoes a polarization rotation. This
magneto-optical Kerr effect (MOKE) has been intensively studied in a variety of
ferro- and ferrimagnetic materials because it provides a powerful probe for
electronic and magnetic properties as well as for various applications
including magneto-optical recording. Recently, there has been a surge of
interest in antiferromagnets (AFMs) as prospective spintronic materials for
high-density and ultrafast memory devices, owing to their vanishingly small
stray field and orders of magnitude faster spin dynamics compared to their
ferromagnetic counterparts. In fact, the MOKE has proven useful for the study
and application of the antiferromagnetic (AF) state. Although limited to
insulators, certain types of AFMs are known to exhibit a large MOKE, as they
are weak ferromagnets due to canting of the otherwise collinear spin structure.
Here we report the first observation of a large MOKE signal in an AF metal at
room temperature. In particular, we find that despite a vanishingly small
magnetization of $M \sim$0.002 $\mu_{\rm B}$/Mn, the non-collinear AF metal
Mn$_3$Sn exhibits a large zero-field MOKE with a polar Kerr rotation angle of
20 milli-degrees, comparable to ferromagnetic metals. Our first-principles
calculations have clarified that ferroic ordering of magnetic octupoles in the
non-collinear Neel state may cause a large MOKE even in its fully compensated
AF state without spin magnetization. This large MOKE further allows imaging of
the magnetic octupole domains and their reversal induced by magnetic field. The
observation of a large MOKE in an AF metal should open new avenues for the
study of domain dynamics as well as spintronics using AFMs.

16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess