Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Emergence of a metallic meta-stable phase induced by electrical current
  in Ca_2RuO_4   A comprehensive study of the behavior of the Mott insulator Ca_2RuO_4 under
electrical current drive is performed by combining two experimental probes: the
macroscopic electrical transport and the microscopic X-Ray diffraction. The
resistivity, rho, vs electric current density, J, and temperature, T ,
rho(J,T), resistivity map is drawn. In particular, the meta-stable state,
induced between the insulating and the metallic thermodynamic states by current
biasing Ca_2RuO_4 single crystals, is investigated. Such an analysis, combined
with the study of the resulting RuO_6 octahedra energy levels, reveals that a
metallic crystal phase emerges in the meta-stable regime. The peculiar
properties of such a phase, coexisting with the well-established orthorhombic
insulating and tetragonal metallic phases, allow to explain some of the
unconventional and puzzling behaviors observed in the experiments, as a
negative differential resistivity.

2
The categories of this paper are: math
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol