Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Field-induced Commensurate-Incommensurate phase transition in a
  Dzyaloshinskii-Moriya spiral antiferromagnet   We report an observation of a commensurate-incommensurate phase transition in
a Dzyaloshinskii-Moriya spiral magnet Ba_2CuGe_2O_7. The transition is induced
by applying a magnetic field in the plane of spin rotation. In this experiment
we have direct control over the strength of the commensurate potential, while
the preferred incommensurate period of the spin system remains unchanged.
Experimental results for the period of the soliton lattice and bulk
magnetization as a function of external magnetic field are in quantitative
agreement with theory.

33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys