Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for the presence of the Fulde-Ferrell-Larkin-Ovchinnikov state
  in CeCu$_2$Si$_2$ revealed using $^{63}$Cu NMR   Nuclear magnetic resonance measurements were performed on CeCu$_{2}$Si$_{2}$
in the presence of a magnetic field close to the upper critical field $\mu_{0}
H_{\rm c2}$ in order to investigate its superconducting (SC) properties near
pair-breaking fields. In lower fields, the Knight shift and nuclear
spin-lattice relaxation rate divided by temperature $1/T_1T$ abruptly decreased
below the SC transition temperature $T_{\rm c}(H)$, a phenomenon understood
within the framework of conventional spin-singlet superconductivity. In
contrast, $1/T_1T$ was enhanced just below $T_{\rm c}(H)$ and exhibited a broad
maximum when magnetic fields close to $\mu_0H_{\rm c2}(0)$ were applied
parallel or perpendicular to the $c$ axis, although the Knight shift decreased
just below $T_{\rm c}(H)$. This enhancement of $1/T_1T$, which was recently
observed in the organic superconductor $\kappa$-(BEDT-TTF)$_{2}$Cu(NCS)$_{2}$,
suggests the presence of high-density Andreev bound states in the inhomogeneous
SC region, a hallmark of the Fulde-Ferrell-Larkin-Ovchinnikov phase.

12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math