Thermal Conductivity and Spin State of the Spin Diamond-Chain System Azurite Cu3(CO3)2(OH)2
Abstract
To investigate the spin state of azurite, Cu3(CO3)2(OH)2, we have measured the thermal conductivity along the c-axis, κc, perpendicular to the spin diamond chains. It has been found that the temperature dependence of κc shows a broad peak at ∼100 K, which is explained as being due to the strong phonon scattering by the strong spin fluctuation owing to the spin frustration at low temperatures below ∼100 K. Furthermore, it has been found that the temperature dependence of κc shows another peak at low temperatures below 20 K and that κc is suppressed by the application of magnetic field along the c-axis at low temperatures below ∼35 K. In high magnetic fields above ∼8 T at low temperatures below ∼6 K, it has been found that κc increases with increasing field. The present results have indicated that both spin-singlet dimers with a spin gap of ∼35 K and antiferromagnetically correlated spin chains with the antiferromagnetic exchange interaction of ∼5.4 K are formed at low temperatures, which is consistent with the recent conclusion by Jeschke et al. [http://doi.org/10.1103/PhysRevLett.106.217201, Phys. Rev. Lett. 106, 217201 (2011)] that the ground state of spins in azurite in zero field is a spin-fluid one. In addition, a new quantum critical line in magnetic fields at temperatures above 3 K has been proposed to exist.
- Publication:
-
Journal of the Physical Society of Japan
- Pub Date:
- March 2016
- DOI:
- 10.7566/JPSJ.85.034715
- arXiv:
- arXiv:1512.08624
- Bibcode:
- 2016JPSJ...85c4715H
- Keywords:
-
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 12 pages, 4 figures, accepted for publication in Journal of the Physical Society of Japan