Influence of morphology in the magnetic properties of layered double hydroxides

We report the controlled synthesis of magnetic CoAl and NiFe layered double hydroxides (LDHs) endowed with well-defined morphology (hexagonal and flower-like shapes) by means of modified homogeneous precipitation. These layered magnets display high crystallinity and micrometric size, thus offering a perfect scenario for the elucidation of the role exerted by distortion of the layers in their magnetic behaviour. The magnetic properties have been investigated by means of DC and AC magnetic susceptibility measurements and isothermal magnetization, demonstrating that the distortion of the nanosheets induces a magnetically more disordered behaviour, with marked spin-glass nature, independently of the composition of the layers. This is reflected in a more antiferromagnetic character, lower coercive fields, higher values of saturation magnetization and higher activation energies. Moreover, the temperatures for the onset of the spontaneous magnetization of the distorted systems reached the highest values reported so far. This work highlights for the very first time the importance of the morphology on the magnetic behaviour of LDHs and will serve as a guide in the design of new switchable magnetic hybrids.