Article

# Linear temperature dependence of the magnetic heat conductivity in CaCu2O3.

Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01171 Dresden, Germany.

Physical Review Letters (Impact Factor: 7.73). 02/2007; 98(2):027201. DOI: 10.1103/PhysRevLett.98.027201 Source: PubMed

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**ABSTRACT:**We study the spin-phonon drag effect in the magnetothermal transport of spin-1/2 two-leg ladders coupled to lattice degrees of freedom. Using a bond operator description for the triplon excitations of the spin ladder and magnetoelastic coupling to acoustic phonons, we employ the time convolutionless projection operator method to derive expressions for the diagonal and off-diagonal thermal conductivities of the coupled two-component triplon-phonon system. We find that for magnetoelastic coupling strengths and diagonal scattering rates relevant to copper-oxide spin-ladders the drag heat conductivity can be of similar magnitude as the diagonal triplon heat conductivity. Moreover, we show that the drag and diagonal conductivities display very similar overall temperature dependences. Finally, the drag conductivity is shown to be rather susceptible to external magnetic fields.05/2013; - [Show abstract] [Hide abstract]

**ABSTRACT:**We report a study on the heat transport of an S = 1 Haldane chain compound Ni(C3H10N2)2NO2ClO4 at low temperatures and in magnetic fields. The zero-field thermal conductivities show a remarkable anisotropy for the heat current along the spin-chain direction (κb) and the vertical direction (κc), implying a magnetic contribution to the heat transport along the spin-chain direction. The magnetic-field-induced change of the spin spectrum has obviously opposite impacts on κb and κc. In particular, κb(H) and κc(H) curves show peak-like increases and dip-like decreases, respectively, at ∼9 T, which is the critical field that minimizes the spin gap. These results indicate a large magnetic thermal transport in this material.Journal of Applied Physics 03/2013; 113(17). · 2.21 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We investigate the Heisenberg-Kitaev chain in order to uncover the interplay between two qualitatively different integrable points in the physics of heat transport in one-dimensional spin liquids. Based on linear response theory and analytical as well as numerical approaches, we explore several directions in parameter space including exchange-coupling ratios, anisotropies, and external magnetic fields. We show the emergence of purely ballistic energy transport at all integrable points, manifest in pronounced Drude weights and low-frequency suppression of regular-conductivity contributions. Moreover, off integrability, we find extended quantum chaotic regions with vanishing Drude weights and well-defined DC conductivities. In the vicinity of the Kitaev point, we observe clear signatures of the topological gap in the response function.Preprint. 12/2013;

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