Investigations of the heterometallic ludwigite NiAlBO.

We present magnetic, thermodynamic, dielectric and structural investigations on the aluminoborate NiAlBO, belonging to the ludwigite family. Room temperature structural refinement suggests that the system crystallizes in the orthorhombic Pbam symmetry, in similarity with most members of this material class. Magnetic and thermodynamic measurements shows that the system undergoes a phase transition to an antiferromagnetic state at 38 K, signatures of which are also seen in the lattice parameters and the dielectric constant. Short range magnetic correlations appear to persist to much higher temperatures-a regime in which the ac susceptibility exhibits a power law temperature dependence, in agreement with that expected for random exchange Heisenberg antiferromagnetic spin chains.