Magnetic structure of (C5H12N)CuBr3: origin of the uniform Heisenberg chain behavior and the magnetic anisotropy of the Cu2+ (S = 1/2) ions

Abstract

The magnetic properties and electric polarization of the organic/inorganic hybrid system (C5H12N)CuBr3 (C5H12N = piperidinium) were examined on the basis of density functional theory calculations. The spin exchanges of (C5H12N)CuBr3 evaluated by energy-mapping analysis show that its uniform Heisenberg antiferromagnetic chain behavior is not caused by the CuBr3 chains made up of edge-sharing CuBr5 square pyramids, but by the two-leg spin ladders resulting from interchain interactions. The magnetic anisotropy of the Cu2+ ions in (C5H12N)CuBr3 originates largely from the Br- ligands rather than the Cu2+ ions. The electric polarization of (C5H12N)CuBr3 arises from the absence of inversion symmetry in the crystal structure, and is weakly affected by the magnetic structure.