Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Broken rotational symmetry in the pseudogap phase of a high-Tc
  superconductor   The nature of the pseudogap phase is a central problem in the quest to
understand high-Tc cuprate superconductors. A fundamental question is what
symmetries are broken when that phase sets in below a temperature T*. There is
evidence from both polarized neutron diffraction and polar Kerr effect
measurements that time- reversal symmetry is broken, but at temperatures that
differ significantly. Broken rotational symmetry was detected by both
resistivity and inelastic neutron scattering at low doping and by scanning
tunnelling spectroscopy at low temperature, but with no clear connection to T*.
Here we report the observation of a large in-plane anisotropy of the Nernst
effect in YBa2Cu3Oy that sets in precisely at T*, throughout the doping phase
diagram. We show that the CuO chains of the orthorhombic lattice are not
responsible for this anisotropy, which is therefore an intrinsic property of
the CuO2 planes. We conclude that the pseudogap phase is an electronic state
which strongly breaks four-fold rotational symmetry. This narrows the range of
possible states considerably, pointing to stripe or nematic orders.

21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph