Long-range antiferromagnetic order in quasi-one-dimensional and

Specific heat, elastic neutron scattering, and torque measurements have been performed on the two quasi-one-dimensional cuprates (Formula presented) and (Formula presented) These compounds consist of infinite (Formula presented) chains, which are highly hole doped. In both compounds a peak in the specific heat, attributed to a static magnetic transition, has been observed at (Formula presented) Magnetic Bragg peaks were identified in the neutron diffraction patterns, giving evidence of a three-dimensional long-range ordered ground state. © 1998 The American Physical Society.