The bulk magnetic properties of the new quasi-one-dimensional Heisenberg antiferromagnet, CuCrO4, were characterized by magnetic susceptibility, heat capacity, optical spectroscopy, EPR and dielectric capacitance measurements and density functional evaluations of the intra-and inter-chain spin exchange interactions. We found type-II multiferroicity below the Néel temperature of 8.2(5) K, arising from competing antiferromagnetic nearest-neighbor (Jnn) and next-nearest-neighbor (Jnnn) intra-chain spin exchange interactions. Experimental and theoretical results indicate that the ratio Jnn/Jnnn is close to 2, putting CuCrO4 in the vicinity of the Majumdar-Ghosh point.

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We carried out detailed studies of the magnetic structure, magnetoelastic coupling, and thermal properties of EuCrO3 nano-powders from room temperature to liquid helium temperature. Our neutron powder diffraction and X-ray powder diffraction measurements provide precise atomic positions of all atoms in the cell, especially for the light oxygen atoms. The low-temperature neutron powder diffraction data revealed extra Bragg peaks of magnetic origin which can be attributed to a Gx antiferromagnetic structure with an ordered moment of ∼ 2.4 µB consistent with the 3d 3 electronic configuration of the Cr 3+ cations. Apart from previously reported antiferromagnetic and ferromagnetic transitions in EuCrO3 at low temperatures, we also observed an anomaly at about 100 K. This anomaly was observed in temperature dependence of sample's, lattice parameters, thermal expansion, Raman spectroscopy, permittivity and conductance measurements. This anomaly is attributed to the magnetoelastic distortion in the EuCrO3 crystal.

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EuTiO3 exhibits strong magneto-electric coupling at the onset of antiferromagnetic order below TN = 5.7 K. The dielectric permittivity drops at TN by 7% and recovers to normal values with increasing magnetic field. This effect is shown to stem from tiny lattice effects as seen in magnetostriction data which directly affect the soft optic mode and its polarizability coordinate. By combining experimental results with theory we show that marginal changes in the lattice parameter of the order of 0.01% have a more than 1000% effect on the transverse optic soft mode of ETO and thus easily induce a ferroelectric instability.