Abstract
Based on high-resolution measurements of the thermal expansion and the magnetostriction we analyze the magnetoelastic coupling of . We find that the phase boundary between the low-field spin liquid phase and the magnetic-field-induced Néel phase is extremely sensitive to pressure and would change by about depending on the direction of uniaxial pressure. This drastic effect can unambiguously be traced back to the pressure dependencies of the intradimer coupling, whereas changes of the interdimer couplings under pressure play a minor role. The observed strong decrease of the interdimer coupling, when Tl is substituted by K, is therefore not a consequence of chemical pressure.
- Received 15 December 2004
DOI:https://doi.org/10.1103/PhysRevLett.95.017205
©2005 American Physical Society