Exchange interactions in Cu2AlBO5 and Cu2GaBO5

Single crystals of ludwigite Cu2MeBO5 (Me=Al, Ga) were synthesized by flux growth technique. The calculations of the exchange integrals in frameworks of indirect coupling model revealed that monoclinic distortions strongly affect exchange interactions. We have performed electron spin resonance (ESR) measurements for untwined single crystals of Cu2MeBO5 (Me=Al, Ga). The observed anisotropy of the ESR linewidth result from the one-dimensional chain like structure of Cu2MeBO5 (Me=Al, Ga) and the anisotropic exchange interactions between Cu ions, respectively.