Magnetism in two-dimensional layered double hydroxides

Layered double hydroxides (LDHs) are a class of anionic clays known for a long time and properly classified in the beginning of 20th century. They are composed of positively charged metal hydroxide-based sheets endowed with interlayer anions and solvent molecules to keep the electro-neutrality. LDHs have attracted increasing attention during the last years because of their rich chemical versatility and the fact that they can be exfoliated -or directly synthesized- into two-dimensional (2D) nanosheets, impacting a wide range of potential applications. Among others, magnetism stands out as one of the most appealing properties of LDHs, this is mainly due to the possibility of modulating their magnetic interactions by judicious tuning of their composition, morphology or interlayer spacing. The combination of their modulable physical properties with good processability positions these nanosheets as excellent candidates for the development of hybrid materials and heterostructures. This review addresses from the first reports to the most recent advances in the magnetic properties of LDHs and their hybrids, showing the great potential they hold as 2D quantum materials. In addition, it is also shown how magnetic properties can be useful in energy-related applications, either evaluating the purity of materials of utmost importance such as NiFe-LDHs, or elucidating their cationic order at the atomic scale, which influences the catalytic performance.