Impurity-Ion pair induced high-temperature ferromagnetism in Co-doped ZnO
Impurity-Ion pair induced high-temperature ferromagnetism in Co-doped ZnO
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DOI：
10.1103/physrevb.78.054428
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发表时间：
2008-01
期刊：
影响因子：
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通讯作者：
C. D. Pemmaraju;R. Hanafin;T. Archer;H. Braun;S. Sanvito
中科院分区：
文献类型：
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作者：
C. D. Pemmaraju;R. Hanafin;T. Archer;H. Braun;S. Sanvito
掺杂到宽禁带氧化物中的磁性3d离子显示出室温铁磁性的特征，尽管它们的浓度比常规磁体中的浓度小两个数量级。这些特殊材料的原型是钴掺杂的氧化锌，对其室温铁磁性的解释仍然难以捉摸。在这里，我们证明了磁性来源于Co氧-空位对，其部分填充能级接近于氧化锌导带的最小值。这些对之间的磁相互作用范围足够长，足以在中等浓度下引起渗流。然而，大到足以在室温下表现出滞后的磁关联星团已经在渗流阈值以下形成，并解释了目前的实验结果。我们的工作证明了氧化锌：钴的磁性完全由本征缺陷决定，并给出了相图。这就提出了一种通过控制自旋电子学材料的本征缺陷来调整其磁性的配方。
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 Co 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.