Das Pemmaraju Chaitanya, Sanvito S
Department of Physics, Trinity College, Dublin 2, Ireland.
Phys Rev Lett. 2005 Jun 3;94(21):217205. doi: 10.1103/PhysRevLett.94.217205. Epub 2005 Jun 2.
In view of recent experimental reports of unexpected ferromagnetism in HfO(2) thin films, we carried out first-principles investigations looking for magnetic order possibly brought about by the presence of small concentrations of intrinsic point defects. Ab initio electronic structure calculations using density functional theory show that isolated cation vacancy sites in HfO(2) lead to the formation of high-spin defect states. Furthermore these appear to be ferromagnetically coupled with a rather short range magnetic interaction, resulting in a ferromagnetic ground state for the whole system. More interestingly, the occurrence of these high-spin states and ferromagnetism is in the low symmetry monoclinic phase of HfO(2). This is radically different from other systems previously known to exhibit point defect ferromagnetism, warranting a closer look at the phenomenon.
鉴于最近关于HfO₂薄膜中意外铁磁性的实验报告，我们进行了第一性原理研究，以寻找可能由少量本征点缺陷的存在而导致的磁有序。使用密度泛函理论的从头算电子结构计算表明，HfO₂中孤立的阳离子空位会导致高自旋缺陷态的形成。此外，这些态似乎通过相当短程的磁相互作用发生铁磁耦合，从而导致整个系统呈现铁磁基态。更有趣的是，这些高自旋态和铁磁性的出现是在HfO₂的低对称单斜相中。这与先前已知表现出点缺陷铁磁性的其他系统有根本不同，值得对该现象进行更深入的研究。
