Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Origin of the tetragonal-to-orthorhombic (nematic) phase transition in
  FeSe: a combined thermodynamic and NMR study   The nature of the tetragonal-to-orthorhombic structural transition at
$T_s\approx90$ K in single crystalline FeSe is studied using shear-modulus,
heat-capacity, magnetization and NMR measurements. The transition is shown to
be accompanied by a large shear-modulus softening, which is practically
identical to that of underdoped Ba(Fe,Co)$_2$As$_2$, suggesting very similar
strength of the electron-lattice coupling. On the other hand, a
spin-fluctuation contribution to the spin-lattice relaxation rate is only
observed below $T_s$. This indicates that the structural, or "nematic", phase
transition in FeSe is not driven by magnetic fluctuations.

18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom