Two spin-canting textures in the antiferromagnetic phase AF1 of MnWO4 based on the new polar atomistic model in P2

Abstract

The low temperature antiferromagnetic (AF) phase of MnWO4 (the so-called AF1 phase) exhibits different spin-canting configurations at two Mn2+ sublattices of the (3 + 1)-dimensional magnetic structure. The suggested superspace group is a significant consequence of the polar space group 2 true for the nuclear structure of MnWO4. Density functional theory calculations showed that its ground state prefers this two spin-canting system. The structural difference between two independent atomic sites for Mn (Mna, Mnb) is too small to allow microscopically detectable electric polarisation. However, this hidden intrinsic polar character allows AF1 two commensurately modulated spin-canting textures. This is considered as the prerequisite onset of the improper ferroelectricity enhanced by the helical spin order in the multiferroic phase AF2 of MnWO4.