Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Tunneling in Ferrimagnetic Nanoparticles Coupled to a Spin Bath:
  An Effective Hamiltonian   An effective Hamiltonian, describing quantum tunneling in ferrimagnetic
nanoparticles which includes interactions between the electronic spins of
nanoparticle and microscopic environmental spins (like nuclear spins or
paramagnetic impurities), is obtained. Two limiting cases, describing tunneling
in antiferromagnetic and ferromagnetic regimes are considered, and criterion
for the transition between the two regimes is found. The validity of analytic
results is verified by the exact diagonalization method.

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The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex