On the peculiar properties of triangular-chain EuCr3(BO3)4 antiferromagnet

In this paper we report studies on EuCr3(BO3)4 compound, that is a member of newly discovered family of huntite-related specimens for non-linear optics. For the first time, the uncommon temperature dependence of the EuCr3(BO3)4 lattice parameters is reported. Additionally, the magnetism of this compound is extremely interesting. Namely, a possible interplay in between potentially magnetic rare-earth ions and 3d metal stacked within quasi-1D chain that can lead to a great variety of magnetic behaviour. Indeed, in our studies we have found 3D-long range ordering with metamagnetic behaviour, while at higher temperature the magnetic chains become uncoupled. Torsion-like vibrations are the key to understand negative thermal expansion along the a-axis. [Display omitted] •EuCr3(BO3)4 is a peculiar triangular-chain antiferromagnet.•Rare earth sublattice is non-magnetic with Eu3+ configuration.•Cr3+ magnetic moments show 1-D behaviour along with spin fluctuations.•Torsion vibrations of Cr triangular tubes lead to anomalous expansion of unit cell.