Relationship between ferroelectricity and magnetic structure of PbCuSO4(OH)2 with CuO2 ribbon chains

Abstract

Neutron diffraction, magnetization and dielectric constant have been measured for single-crystal samples of PbCuSO4(OH)2 with quasi one-dimensional spin-1/2 chains formed of edge-sharing CuO4 square planes called CuO2 ribbon chains. An antiferromagnetic transition with an incommensurate helical magnetic ordering and a ferroelectric transition have been found to appear simultaneously at TN∼2.8 K. From the neutron diffraction studies, 0 k±δ l/2 (k = even, l = integer) superlattice magnetic reflections with incommensurate modulation δ∼0.189 have been found below TN. Based on the neutron diffraction and magnetization measurements, the magnetic structure and the relationship to the ferroelectricity are discussed.