Engineering Magnetic Phases in Two-Dimensional Non-van der Waals Transition-Metal Oxides
Engineering Magnetic Phases in Two-Dimensional Non-van der Waals Transition-Metal Oxides
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DOI：
10.1021/acs.nanolett.9b02801
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发表时间：
2019-11-01
期刊：
影响因子：
10.8
通讯作者：
Shenoy, Vivek B.
中科院分区：
文献类型：
--
作者：
Bandyopadhyay, Arkamita;Frey, Nathan C.;Shenoy, Vivek B.
由于可剥离范德华磁性系统的快速发现，二维磁性材料家族正在不断扩大。最近，从普通铁矿石中合成非范德华磁性“血红烯”，为二维材料的发现开辟了一条非传统途径。这些非范德华二维系统化学稳定且易于获得，并且与范德华对应物相比可能具有不同或增强的特性。在这项工作中，我们研究并解释了非范德华二维金属氧化物中磁有序的性质。二维血烯被发现是完全氧钝化的并且在环境条件下稳定。它表现出具有小净磁矩的条纹亚铁磁基态。预测超交换相互作用可以控制血烯的磁性基态，其中压力引起的自旋交叉导致可观察到的净磁矩。通过合金化血烯来调节超交换会改变磁序，将系统调整到铁磁基态。将此策略扩展到新的 2D 材料的设计中，我们提出了 2D 氧化铬（α-Cr2O3）或“色烯”，由于过渡金属间距离较大且 AFM 超交换受到抑制，它具有铁磁基态。我们还表明，调整这些材料中的磁序可以通过调节带隙来控制传输特性，这可能可用于自旋电子或催化应用。
The family of 2D magnetic materials is continuously expanding because of the rapid discovery of exfoliable van der Waals magnetic systems. Recently, the synthesis of non-van der Waals magnetic "hematene" from common iron ore has opened an unconventional route to 2D material discovery. These non-van der Waals 2D systems are chemically stable and easily available and may have different or enhanced properties compared to their van der Waals counterparts. In this work, we have investigated and explained the nature of magnetic ordering in non-van der Waals 2D metal oxides. Two-dimensional hematene is found to be fully oxygen-passivated and stable under ambient conditions. It exhibits a striped ferrimagnetic ground state with a small net magnetic moment. Superexchange interactions are predicted to control the magnetic ground state of hematene, where pressure-induced spin crossover results in an observable net magnetic moment. Modulating the superexchange by alloying hematenes alters the magnetic ordering, tuning the system to a ferromagnetic ground state. Extending this strategy to the design of a new 2D material, we propose 2D chromia (alpha-Cr2O3) or "chromene", which, because of larger inter-transition metal distances and suppressed AFM superexchange, has a ferromagnetic ground state. We also show that tuning the magnetic ordering in these materials controls the transport properties by modulating the band gap, which may be of use in spintronic or catalytic applications.