Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Plastic vortex creep and dimensional crossovers in the highly
  anisotropic superconductor HgBa$_2$CuO$_{4+x}$   In type-II superconductors exposed to magnetic fields between upper and lower
critical values, $H_{c1}$ and $H_{c2}$, penetrating magnetic flux forms a
lattice of vortices whose motion can induce dissipation. Consequently, the
magnetization $M$ of superconductors is typically progressively weakened with
increasing magnetic field $B \propto n_v$ (for vortex density $n_v$). However,
some materials exhibit a non-monotonic $M(B)$, presenting a maximum in $M$ at
what is known as the second magnetization peak. This phenomenon appears in most
classes of superconductors, including low $T_c$ materials, iron-based, and
cuprates, complicating pinpointing its origin and garnering intense interest.
Here, we report on vortex dynamics in optimally doped and overdoped
HgBa$_2$CuO$_{4+x}$ crystals, with a focus on a regime in which plastic
deformations of the vortex lattice govern magnetic properties. Specifically, we
find that both crystals exhibit conspicuous second magnetization peaks and,
from measurements of the field- and temperature- dependent vortex creep rates,
identify and characterize phase boundaries between elastic and plastic vortex
dynamics, as well as multiple previously unreported transitions within the
plastic flow regime. We find that the second magnetization peak coincides with
the elastic-to-plastic crossover for a very small range of high fields, and a
sharp crossover within the plastic flow regime for a wider range of lower
fields. We find evidence that this transition in the plastic flow regime is due
to a dimensional crossover, specifically a transition from 3D to 2D plastic
dynamics.

24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom