Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Weakly coupled alternating $S=1/2$ chains in the distorted honeycomb
  lattice compound Na$_2$Cu$_2$TeO$_6$   Spin-1/2 chains with alternating antiferromagnetic (AF) and ferromagnetic
(FM) couplings exhibit quantum entanglement like the integer-spin Haldane
chains and might be similarly utilized for quantum computations. Such
alternating AF-FM chains have been proposed to be realized in the distorted
honeycomb-lattice compound Na$_2$Cu$_2$TeO$_6$, but to confirm this picture a
comprehensive understanding of the exchange interactions including terms
outside of the idealized model is required. Here we employ neutron scattering
to study the spin dynamics in Na$_2$Cu$_2$TeO$_6$ and accurately determine the
coupling strengths through the random phase approximation and density
functional theory (DFT) approaches. We find the AF and FM intrachain couplings
are the dominant terms in the spin Hamiltonian, while the interchain couplings
are AF but perturbative. This hierarchy in the coupling strengths and the
alternating signs of the intrachain couplings can be understood through their
different exchange paths. Our results establish Na$_2$Cu$_2$TeO$_6$ as a
weakly-coupled alternating AF-FM chain compound and reveal the robustness of
the gapped ground state in alternating chains under weak interchain couplings.

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The categories of this paper are: cs
23
The categories of this paper are: solv-int
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The categories of this paper are: math
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph