Abstract
We report on magnetization measurements of , with , in magnetic fields up to . The low-temperature magnetic response of the spin chains changes strongly upon doping. For , the ground state with nearly independent dimers is confirmed. A reduction of the number of holes in the chains through Ca doping leads to an additional contribution to the magnetization, which depends linearly on the magnetic field. Remarkably, the slope of this linear contribution increases with the Ca content. We argue that antiferromagnetic spin chains do not account for this behavior but that the hole dynamics might be involved.
- Received 4 May 2005
DOI:https://doi.org/10.1103/PhysRevB.72.184406
©2005 American Physical Society