Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Universal Magnetic Properties of $La_{2-\delta} Sr_{\delta} Cu O_4$ at
  Intermediate Temperatures   We present the theory of two-dimensional, clean quantum antiferromagnets with
a small, positive, zero temperature ($T$) stiffness $\rho_s$, but with the
ratio $k_B T / \rho_s $ arbitrary. Universal scaling forms for the uniform
susceptibility ($\chi_u$), correlation length($\xi$), and NMR relaxation rate
($1/T_1$) are proposed and computed in a $1/N$ expansion and by Mont\'{e}-Carlo
simulations. For large $k_B T/\rho_s$, $\chi_u (T)/T$ and $T\xi(T)$ asymptote
to universal values, while $1/T_{1}(T)$ is nearly $T$-independent. We find good
quantitative agreement with experiments and some numerical studies on
$La_{2-\delta} Sr_{\delta} Cu O_4$.

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The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin