Wasp-waisted behavior in magnetic hysteresis curves of CoFe2O4 nanopowder at a low temperature: experimental evidence and theoretical approach

We theoretically and experimentally investigated wasp-waisted magnetic hysteresis curves at a low temperature for CoFe2O4 nanopowders. Our theoretical approach proposes a physical mechanism that leads to wasp-waisted behavior for a single magnetic phase with the same anisotropic field, contrary to that of typical multi-phase magnetic systems. Our simulations show that a combination of effects, namely easy-plane anisotropy configuration and dipolar interactions, results in a double peak in the magnetic susceptibility curve of a granular magnetic system. As experimental evidence of such an effect, we present a CoFe2O4 nanopowder and its structural and magnetic characterizations, which support a single magnetic phase. In addition, the evidence does not corroborate many explanations reported in the literature for wasp-waisted magnetic behavior. Our results provide evidence for a tetragonal crystalline phase of CoFe2O4 due to magneto-elastic coupling, recently reported in the literature.