Thermal Conductivity in the Bose-Einstein Condensed State of Triplons in the Bond-Alternating Spin-Chain System Pb2V3O9

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, $kapp{a}_{\Vert [101]}$, and perpendicular to spin-chains, $kapp{a}_{\perp [101]}$, of the S=1/2 bond-alternating spin-chain system Pb2V3O9 in magnetic fields up to 14 T. With increasing field at 3 K, it has been found that both $kapp{a}_{\Vert [101]}$ and $kapp{a}_{\perp [101]}$ 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, $kapp{a}_{\Vert [101]}$ is enhanced with increasing field, while $kapp{a}_{\perp [101]}$ 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 $kapp{a}_{\Vert [101]}$ 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 4He.

5 pages, 3 figures

References in corpus (1)

• Drastic enhancement of magnon thermal conductivity in the Bose-Einstein condensed state of TlCuCl${}_3$

Cited by in corpus (1)

• Thermal Conductivity of the S = 1/2 Quasi-One-Dimensional Ferromagnetic Spin System CsCuCl3