Formation of Co nanodisc with enhanced perpendicular magnetic anisotropy driven by
Formation of Co nanodisc with enhanced perpendicular magnetic anisotropy driven by
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具有增强的垂直磁各向异性的Co纳米盘的形成
DOI：
10.1103/physrevb.94.174422
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
and A.Maziewski
中科院分区：
文献类型：
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作者：
M.Sakamaki;K.Amemiya;I.Sveklo;P.Mazalski;M.O.Liedke;J.Fassbender;Z.Kurant;A.Wawro;and A.Maziewski
利用X射线磁性圆二色性（XMCD）和扩展X射线吸收精细结构（EXAFS）分析研究了Pt/Co/Pt薄膜在~注量下离子辐照后从面内磁各向异性到垂直磁各向异性（PMA）的磁相变起源。我们发现，Pt和Co原子是相互混合的，并且由于除去Pt覆盖层，Co在表面附近被氧化。极化相关EXAFS分析表明，Co首先以单原子厚度的片状分散在Pt基体中，然后在处Co片被分成若干团簇，这些团簇被认为是平行于薄膜平面的纳米盘。该过程伴随着面外磁化分量的出现，并且观察到剩磁峰。因为我们没有观察到Co轨道矩的各向异性的增强，这导致磁各向异性通过在约的转变而改变，所以这种纳米盘的形成可能通过形状效应诱导磁各向异性的增加。通过与在较低注量下观察到的相变[Phys. Rev. B 86，024418（2012）PRBMDO 1098 -012110.1103/PhysRevB.86.024418]进行比较，我们发现两种相变的机制是不同的，即，在较低能量密度下的转变是由结构应变引起的轨道矩的各向异性引起的，而目前的转变可能是由于纳米盘形成引起的形状效应。
The origin of magnetic phase transition from in-plane to perpendicular magnetic anisotropy (PMA) of Pt/Co/Pt thin film byion irradiation at fluences ofis investigated by means of x-ray magnetic circular dichroism (XMCD) and extended x-ray absorption fine structure (EXAFS) analyses. We find that Pt and Co atoms are mixed with each other and that Co is oxidized near the surface due to removal of the Pt overlayer. Furthermore, polarization-dependent EXAFS analysis shows that Co is firstly dispersed as separated single-atom-thick sheets in a Pt matrix at, then the Co sheets are divided into a fewclusters at, which are regarded as nanodiscs parallel to the film plane. This process is accompanied by the appearance of an out-of-plane magnetization component and a remanence peak is observed. Because we do not observe an enhancement in anisotropy of Co orbital moment which leads to change in magnetic anisotropy through the transition at about, it might be possible that such nanodisc formation induces increase of magnetic anisotropy via a shape effect. By comparing with the phase transition observed at lower fluence [Phys. Rev. B 86, 024418 (2012)PRBMDO1098-012110.1103/PhysRevB.86.024418], we find that the mechanism of two transitions is different, i.e., the transition at lower fluence is caused by anisotropy of orbital moment due to structural strain, while the present transition is possibly by shape effect due to nanodisc formation.