Effect of Spin Dilution on the Magnetic State of Delafossite CuFeO2 with an S = 5/2 Antiferromagnetic Triangular Sublattice

Abstract

This work describes the scandium doping effect on the structural and magnetic properties of delafossite-type oxides CuCr1−x Sc x O2. The lattice parameters were found to vary according to Vegard’s low. A reflection broadening is observed that is ascribed to local lattice distortion due to the ionic radius difference between Fe3+ and Sc3+. Magnetic susceptibility measurements show that the dominant interactions are antiferromagnetic (AFM) but that doping induces significant changes. A rather monotonous T N2 decrease as x increases, from T N2 = 9.1 K down to T N2 = 5.9 K for x = 0.00 to 0.25, respectively, but T N1 remains almost unchanged. The Sc substitution (S = 0) at the Fe sites (S = 5/2) tend to suppress the low ferromagnetic interactions in the magnetic structure; however, the magnetic exchange coupling J BB decreases under 5.0 meV with increasing x. The electric polarization decreases with x up to 63 μC/m2 for 5 %-Sc to 22 μC/m2 for 25 %-Sc.