Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum magnetism of perfect spin tetrahedra in Co$_{4}$B$_{6}$O$_{13}$   Co$_{4}$B$_{6}$O$_{13}$ contains undistorted tetrahedral clusters of magnetic
Co$^{2+}$ ions. The high-field magnetization of this magnet exhibits a periodic
undulation indicating quantization of the total spin number per cluster.
Measurements of magnetic susceptibility and specific heat reveal that the
ground state is composed of several different singlet states, reflecting the
high symmetry of the spin tetrahedron. An exact diagonalization calculation
taking account of single-ion type anisotropies and Dzyaloshinsky-Moriya
interactions reproduces the expretimental results very well.

20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th