Abstract
Neutron diffraction was used to determine the crystal structure and magnetic ordering pattern of a single crystal, with and without applied magnetic field. A previously unreported, subtle monoclinic distortion of the crystal structure away from the orthorhombic space group was detected. The distortion is also present in lightly Sr-doped crystals. A refinement of the crystal structure shows that the deviation from orthorhombic symmetry is predominantly determined to drive a continuous reorientation of the copper spins from the orthorhombic axis to the axis, directly confirming predictions based on prior magnetoresistance and Raman scattering experiments. A spin-flop transition induced by a -axis oriented field previously reported for nonstoichiometric is also observed, but the transition field is significantly larger than that in the previous work.
- Received 23 January 2006
DOI:https://doi.org/10.1103/PhysRevB.73.144513
©2006 American Physical Society