Impurity-Ion pair induced high-temperature ferromagnetism in Co-doped ZnO

Abstract

Magnetic 3d-ions doped into wide-gap oxides show signatures of room temperature ferromagnetism, although their concentration is two orders of magnitude smaller than that in conventional magnets. The prototype of these exceptional materials is Co-doped ZnO, for which an explanation of the room temperature ferromagnetism is still elusive. Here we demonstrate that magnetism originates from Co2+ oxygen-vacancy pairs with a partially filled level close to the ZnO conduction band minimum. The magnetic interaction between these pairs is sufficiently long-ranged to cause percolation at moderate concentrations. However, magnetically correlated clusters large enough to show hysteresis at room temperature already form below the percolation threshold and explain the current experimental findings. Our work demonstrates that the magnetism in ZnO:Co is entirely governed by intrinsic defects and a phase diagram is presented. This suggests a recipe for tailoring the magnetic properties of spintronics materials by controlling their intrinsic defects.

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Cited by in corpus (16)

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• Band-edge problem in the theoretical determination of defect energy levels: the O vacancy in ZnO as a benchmark case
• Manybody GW calculation of the oxygen vacancy in ZnO
• Electron doping and magnetic moment formation in N- and C-doped MgO
• Monte Carlo simulation of magnetic phase transitions in Mn doped ZnO
• Electronic structure and magnetism of transition metal doped Zn12O12 clusters: Role of defects
• Electronic structure of Co doped ZnO from the \textit{GW} perspective
• The magnetism of wurtzite CoO nanoclusters
• Impurity-vacancy complexes and ferromagnetism in doped sesquioxides
• Magnetic properties of isolated Re ion and Re-Re complex in ZnO studied by GGA +U approach
• Calculated optical properties of Co in ZnO: internal and ionization transitions
• Magnetic interaction of Co ions near the {10\bar{1}0} ZnO surface
• Reduction of conductivity and ferromagnetism induced by Ag doping in ZnO:Co
• Searching for high magnetization density in bulk Fe: the new metastable Fe${}_6$ phase
• Spiral magnetism and chiral superconductivity in Kondo-Hubbard triangular lattice model