Strong ferromagnetism at the surface of an antiferromagnet caused by buried magnetic moments
Strong ferromagnetism at the surface of an antiferromagnet caused by buried magnetic moments
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DOI：
10.1038/ncomms4171
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发表时间：
2013-12
影响因子：
16.6
通讯作者：
A. Chikina;M. Höppner;S. Seiro;K. Kummer;S. Danzenbächer;Swapnil Patil;A. Generalov;M. Güttler-
中科院分区：
文献类型：
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作者：
A. Chikina;M. Höppner;S. Seiro;K. Kummer;S. Danzenbächer;Swapnil Patil;A. Generalov;M. Güttler-
二价铕在半填充的 4f 壳层中每个原子携带 7μB 的大纯自旋磁矩，是组装新型磁性器件的杰出元素，其中二维电子气可能由于与下面的磁活性 Eu 层的交换相互作用而被极化。在这里，我们发现反铁磁体 EuRh2Si2 的 Si-Rh-Si 表面三层具有表面态，该表面态表现出意想不到的、可通过温度控制的大自旋分裂。分裂发生在~32.5 K以下，远高于主体中Eu 4f矩的有序温度（~24.5 K），表明最顶层Eu层中存在较大的有序温度。表面巡回铁磁性的驱动力是上述交换相互作用。这种分裂也可以被诱导成沉积在EuRh2Si2或具有金属或半导体特性的类似有序磁性材料的表面上的功能表面层的状态。
Carrying a large, pure spin magnetic moment of 7 μB per atom in the half-filled 4fshell, divalent europium is an outstanding element for assembling novel magnetic devices in which a two-dimensional electron gas may be polarized due to exchange interaction with an underlying magnetically-active Eu layer. Here we show that the Si-Rh-Si surface trilayer of the antiferromagnet EuRh2Si2bears a surface state, which exhibits an unexpected and large spin splitting controllable by temperature. The splitting sets in below ~32.5 K, well above the ordering temperature of the Eu 4fmoments (~24.5 K) in the bulk, indicating a larger ordering temperature in the topmost Eu layers. The driving force for the itinerant ferromagnetism at the surface is the aforementioned exchange interaction. Such a splitting may also be induced into states of functional surface layers deposited onto the surface of EuRh2Si2or similarly ordered magnetic materials with metallic or semiconducting properties.