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arXiv:1010.6237 · Journal of Physics Conference Series

Thermal conductivity in the Bose-Einstein Condensed state of triplons in the bond-alternating spin-chain system Pb2V3O9

Mitsuhide Sato, Takayuki Kawamata, Naoki Sugawara, Naoto Kaneko, Masanori Uesaka, Kazutaka Kudo, Norio Kobayashi, Yoji Koike

Published Jan 1, 2010• 3 citations
arXivHTMLPDF

Abstract

In order to clarify the origin of the enhancement of the thermal conductivity in the Bose-Einstein Condensed (BEC) state of field-induced triplons, we have measured the thermal conductivity along the [101] direction parallel to spin-chains, κ ||[101] , and perpendicular to spin-chains, κ ⊥[101] , of the S =1/2 bond-alternating spin-chain system Pb 2 V 3 O 9 in magnetic fields up to 14 T. With increasing field at 3 K, it has been found that both κ ||[101] and κ ⊥[101] are suppressed in the gapped normal state in low fields. In the BEC state of field-induced triplons in high fields, on the other hand, κ ||[101] is enhanced with increasing field, while κ ⊥[101] is suppressed. That is, the thermal conductivity along the direction, where the magnetic interaction is strong, is markedly enhanced in the BEC state. Accordingly, our results suggest that the enhancement of κ ||[101] in the BEC state is caused by the enhancement of the thermal conductivity due to triplons on the basis of the two-fluid model, as in the case of the superfluid state of liquid 4 He.

DOI
10.1088/1742-6596/200/2/022054

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In order to clarify the origin of the enhancement of the thermal conductivity in the Bose-Einstein Condensed (BEC) state of field-induced triplons, we have measured the thermal conductivity along the [101] direction parallel to spin-chains, κ ||[101] , and perpendicular to spin-chains, κ ⊥[101] , of the S =1/2 bond-alternating spin-chain system Pb 2 V 3 O 9 in magnetic fields up to 14 T. With increasing field at 3 K, it has been found that both κ ||[101] and κ ⊥[101] are suppressed in the gapped normal state in low fields. In the BEC state of field-induced triplons in high fields, on the other hand, κ ||[101] is enhanced with increasing field, while κ ⊥[101] is suppressed. That is, the thermal conductivity along the direction, where the magnetic interaction is strong, is markedly enhanced in the BEC state. Accordingly, our results suggest that the enhancement of κ ||[101] in the BEC state is caused by the enhancement of the thermal conductivity due to triplons on the basis of the two-fluid model, as in the case of the superfluid state of liquid 4 He.
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