Synthesis, characterization, and mechanism analysis of S = 2 quasi-one-dimensional ferromagnetic semiconductor Pb2Mn(VO4)2(OH)

Abstract

A brackebuschite-type compound Pb₂Mn(VO₄)₂(OH) was synthesized by a hydrothermal method. Single crystal X-ray diffraction reveals that Pb₂Mn(VO₄)₂(OH) crystallizes in the space group P2₁/m, with the structure built of single [010] chains of edge-shared MnO₆ octahedra bridged by VO₄–PbO₆ groups along a and c axes, as a result forming a very large inter-chain distance of about 7.67 Å. The magnetic and optical measurements indicate that Pb₂Mn(VO₄)₂(OH) is an S = 2 quasi-one-dimensional ferromagnetic semiconductor, with a very small specific value of intra- and inter-chain exchange coupling J_intra/J_inter = 10⁻³, and a band gap of 1.72 eV. The electronic structure calculations indicate that a 90° Mn–O–Mn dpσ–dpσ correlation superexchange dominates the intra-chain ferromagnetic coupling in Pb₂Mn(VO₄)₂(OH).