Recently, monolayer hematite termed hematene (FeO₂) was exfoliated from its non-van der Waals bulk counterpart (α-Fe₂O₃), and found to prefer ferromagnetic ordering at around room temperature. However, the underlying mechanism of its room temperature ferromagnetism has not been convincingly established. Here, by combining the particle swarm method, first-principles calculations, and Monte Carlo simulations, we reexamine the magnetism of monolayer hematite. It is confirmed that the ground state of infinite two-dimensional hematene possesses the 1T phase similar to MoS₂ and antiferromagnetic exchange coupling between the iron atoms. In contrast to its three-dimensional bulk counterpart, the two-dimensional hematene does not switch into the ferromagnetic phase at room temperature, even in consideration of the Dzyaloshinsky–Moriya interaction. However, it is found that the one-dimensional hematene nanoribbons with width consisting of odd numbers of Fe rows exhibit net magnetic ordering originating from the spin-polarized edge states. The present findings may provide new insights on the magnetism of hematene-based nanostructures.

中文翻译：

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二维 hematene 中的边缘态感应磁性

最近，称为赤铁矿（FeO ₂）的单层赤铁矿从其非范德华体对应物（α-Fe ₂ O ₃）剥离，并发现在室温附近更喜欢铁磁有序。然而，其室温铁磁性的潜在机制尚未得到令人信服的证实。在这里，通过结合粒子群方法、第一性原理计算和蒙特卡罗模拟，我们重新审视了单层赤铁矿的磁性。证实无限二维hematene的基态具有类似于MoS _2的1T相和铁原子之间的反铁磁交换耦合。与其三维体积对应物相比，即使考虑到 Dzyaloshinsky-Moriya 相互作用，二维 hematene 在室温下也不会转变为铁磁相。然而，发现宽度由奇数个 Fe 行组成的一维 hematene 纳米带表现出源自自旋极化边缘状态的净磁性排序。目前的发现可能为基于血红素的纳米结构的磁性提供新的见解。