Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical floating zone crystal growth of rare-earth disilicates,
  $R\mathbf{_{2}}$Si$\mathbf{_{2}}$O$\mathbf{_{7}}$ ($R=$ Er, Ho, and Tm)   The wealth of structural phases seen in the rare-earth disilicate compounds
promises an equally rich range of interesting magnetic properties. We report on
the crystal growth by the optical floating zone method of members of the
rare-earth disilicate family, $R_{2}$Si$_{2}$O$_{7}$ (with $R=$ Er, Ho, and
Tm). Through a systematic study, we have optimised the growth conditions for
Er$_{2}$Si$_{2}$O$_{7}$. We have grown, for the first time using the floating
zone method, crystal boules of Ho$_{2}$Si$_{2}$O$_{7}$ and
Tm$_{2}$Si$_{2}$O$_{7}$ compounds. We show that the difficulties encountered in
the synthesis of polycrystalline and single crystal samples are due to the
similar thermal stability ranges of different rare-earth silicate compounds in
the temperature-composition phase diagrams of the $R$-Si-O systems. The
addition of a small amount of SiO$_{2}$ excess allowed the amount of impurity
phases present in the powder samples to be minimised. The phase composition
analysis of the powder X-ray diffraction data collected on the as-grown boules
revealed that they were of single phase, except in the case of thulium
disilicate, which comprised of two phases. All growths resulted in multi-grain
boules, from which sizable single crystals could be isolated. The optimum
conditions used for the synthesis and crystal growth of polycrystalline and
single crystal $R_{2}$Si$_{2}$O$_{7}$ materials are reported. Specific heat
measurements of erbium and thulium disilicate compounds confirm an
antiferromagnetic phase transition below $T_{\mathrm{N}}=$ 1.8 K for D-type
Er$_{2}$Si$_{2}$O$_{7}$ and a Schottky anomaly centered around 3.5 K in C-type
Tm$_{2}$Si$_{2}$O$_{7}$, suggesting the onset of short-range magnetic
correlations. Magnetic susceptibility data of E-type Ho$_{2}$Si$_{2}$O$_{7}$
reveals an antiferromagnetic ordering of the Ho spins below $T_\mathrm{{N}}=$
2.3 K.

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The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys