Metamagnetic Transitions versus Magnetocrystalline Anisotropy in Two Cobalt Arsenates with 1D Co 2+ Chains

• Published in: Inorganic chemistry 2019-10, Vol.58 (19), p.12609-12617
• Main Authors: Leclercq, Bastien, Kabbour, Houria, Damay, Françoise, Colin, Claire V, Pautrat, Alain, Arevalo-Lopez, Angel M, Mentré, Olivier
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Inorganic chemistry; Material chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b01303

We have investigated two original hydrated cobalt arsenates based on Co octahedral edge-sharing chains. Their different magnetocrystalline anisotropies induce different types of metamagnetic transitions: spin-flop versus spin-flip. In both compounds, a strong local anisotropy (Ising spins) is favored by the spin-orbit coupling present in the CoO octahedra, while ferromagnetic (FM) exchanges predominate in the chains. Co (As O )·2H O ( ) orders antiferromagnetically below = 6.7 K. The magnetic structure is a noncollinear antiferromagnetic spin arrangement along the zigzag chains with DFT calculations implying frustrated chains and weakened anisotropy. A metamagnetic transition suggests a spin-flop process above μ = 3.2 T. In contrast, in BaCo As O ·2H O ( ) linear chains are arranged in disconnected layers, with only interchain ferromagnetic exchanges, therefore increasing its magnetocrystalline anisotropy. The magnetic structure is collinear with a magnetic easy axis that allows a spin-flop to a sharp spin-flip transition below = 15.1 K and above μ H = 6.2 T.