Enhancement of interlayer exchange in an ultrathin two-dimensional magnet
Enhancement of interlayer exchange in an ultrathin two-dimensional magnet
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DOI：
10.1038/s41567-019-0651-0
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发表时间：
2019-12-01
期刊：
影响因子：
19.6
通讯作者：
Jarillo-Herrero, Pablo
中科院分区：
文献类型：
--
作者：
Klein, Dahlia R.;MacNeill, David;Jarillo-Herrero, Pablo
在最近分离单层CH 3之后（参考文献110），(1))，已经分离出更多的二维货车范德华磁性材料（2-12）。它们在货车德瓦耳斯异质结构中的结合为自旋电子学（5-9）、邻近磁性（13）和量子自旋液体（14）提供了一个新的平台。在这个领域的一个主要问题是如何剥离晶体的几层限制影响他们的磁性。对CrI 3的研究表明，与本体相比，CrI 3剥离膜（1，5，6）具有不同的磁基态，但其起源尚不清楚。在这里，我们使用电子隧穿通过几层晶体的层状反铁磁绝缘体CrCl 3探测其磁序，并找到一个十倍的增强层间交换相比，散装晶体。此外，温度和偏振相关的拉曼光谱表明，大块晶体的晶体相变不会发生在剥离膜。这导致了不同的低温堆积顺序，我们假设，增加层间交换。我们的研究提供了对二维磁体中堆叠顺序和层间相互作用之间的联系的深入了解，这可能与将堆垛层错和机械变形与其他更奇特的层状磁体（如RuCl 3）的磁基态相关联有关（参考文献10）。（14））。
Following the recent isolation of monolayer CH3 (ref.(1)), many more two-dimensional van der Waals magnetic materials have been isolated(2-12). Their incorporation in van der Waals hetero-structures offers a new platform for spintronics(5-9), proximity magnetism(13) and quantum spin liquids(14). A primary question in this field is how exfoliating crystals to the few-layer limit influences their magnetism. Studies of CrI3 have shown a different magnetic ground state for ultrathin exfoliated films(1,5,6) compared with the bulk, but the origin is not yet understood. Here, we use electron tunnelling through few-layer crystals of the layered antiferromagnetic insulator CrCl3 to probe its magnetic order and find a tenfold enhancement of the interlayer exchange compared with bulk crystals. Moreover, temperature- and polarization-dependent Raman spectroscopy reveals that the crystallographic phase transition of bulk crystals does not occur in exfoliated films. This results in a different low-temperature stacking order and, we hypothesize, increased interlayer exchange. Our study provides insight into the connection between stacking order and interlayer interactions in two-dimensional magnets, which may be relevant for correlating stacking faults and mechanical deformations with the magnetic ground states of other more exotic layered magnets such as RuCl3 (ref.(14)).