We have measured the thermal conductivity in the frustrated two-leg spin ladder system of Bi(Cu1−xZnx)2PO6 single crystals with x = 0 and 0.02 with the spin quantum number S = 1=2 to investigate the thermal conductivity due to spins, κspin. For x = 0, analogous temperature dependences of the thermal conductivity along the a-axis perpendicular to the spin ladders, κa, and that along the b-axis parallel to the spin ladders, κb, have been observed, indicating that the thermal conductivity due to phonons is dominant in both κa and κb. Moreover, it has been found that a small hump exists at ∼15K only in κb, which becomes clear upon the application of magnetic fields, and is suppressed by the partial substitution of nonmagnetic Zn for Cu. Thus, the hump has been concluded to be due to the contribution of κspin. The magnitude of κspin normalized by the square of the nearest-neighbor exchange interaction, J2, as a function of the temperature normalized by the magnitude of the spin gap, Δ, has been found to be roughly the same as that in another two-leg S = 1=2 spin ladder system, Ca9La5Cu24O41. This means that κspin exists universally in two-leg S = 1=2 spin ladder systems and is roughly scaled by J2 and Δ and that the spin frustration has little influence on κspin.
ASJC Scopus subject areas
- Physics and Astronomy(all)