XANES experimental evidence of double exchange in ferromagnetic Mn–Zn–O

Abstract

Ferromagnetism at room temperature has been observed at the interface between ZnO and MnO₂ in bulk samples. XANES experiments have been performed at the Mn K-edge. Coexistence of Mn³⁺ and Mn⁴⁺ is observed in the ferromagnetic samples, confirming the double exchange mechanism as the responsible for ferromagnetism at room temperature. Using ZnO previously calcined at 950°C as starting material, which has lower diffusion ability than normal ZnO, leads to higher saturation magnetisation values. This indicates that the kinetics of the diffusion of Zn into MnO₂ plays a crucial role in the magnetic properties of this system.

Keywords:

• ZNO
• MNO2
• FERROMAGNETISM
• DOUBLE EXCHANGE
• INTERFACE