Magnetocrystalline anisotropy of La- and Co-substituted M-type strontium ferrites: Role of Co2+ and Fe2

We have systematically investigated the magnetic properties of La- and Co-substituted SrFe12O19 using single crystals. By utilizing the traveling solvent floating zone technique, we have grown single crystals over a wide range of substitution content, and examined their saturation moments and magnetocrystalline anisotropy. With increasing content of La and Co, the saturation moment at 300K monotonically increases. The increment of magnetocrystalline anisotropy is almost proportional to the content of Co. In addition, further La substitution also enhances magnetocrystalline anisotropy, which demonstrates that Fe2+ plays an important role to enhance magnetocrystalline anisotropy. We have analyzed magnetocrystalline anisotropy energy as a function of substitution content, and elucidate the effects of Co2+ and Fe2+.