Recently, ferromagnetism observed in monolayer two-dimensional (2D) materials has attracted attention due to the promise of its application in next-generation spintronics. Here, we predict a symmetry-breaking phase in 2D FeTe₂ that differs from conventional transition metal ditellurides shows superior stability and room-temperature ferromagnetism. Through density functional theory calculations, we find the exchange interactions in FeTe₂ consist of short-range superexchange and long-range oscillatory exchanges mediated by itinerant electrons. For six nearest neighbors, the exchange constants are calculated to be 50.95, 33.41, 2.70, 11.02, 14.46, and −4.12 meV. Furthermore, the strong relativistic effects on Te²⁺ induce giant out-of-plane exchange anisotropy and open up a significantly large spin wave gap (Δ^SW) of 1.22 meV. All of this leads to robust ferromagnetism with the T_c surpassing 423 K, which is predicted by the renormalization group Monte Carlo method, sufficiently higher than room temperature. Our findings shed light on the promising future of FeTe₂ in 2D magnetic research and spintronic applications.

中文翻译：

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室温下具有铁磁性的二维FeTe2中的对称破坏相。

近年来，由于有望在下一代自旋电子学中应用，在单层二维（2D）材料中观察到的铁磁性引起了关注。在这里，我们预测2D FeTe ₂中的对称断裂相与传统的过渡金属二碲化物不同，它表现出优异的稳定性和室温铁磁性。通过密度泛函理论计算，我们发现FeTe _2中的交换相互作用包括短时超交换和流动电子介导的长时振荡交换。对于六个最近的邻居，交换常数计算为50.95、33.41、2.70、11.02、14.46和-4.12 meV。此外，对Te ²⁺有很强的相对论效应诱导出的平面巨交换各向异性，开辟显著大的自旋波的间隙（Δ ^SW 1.22兆电子伏的）。所有这些导致铁磁性强健，T _c超过423 K，这是通过重归一化群蒙特卡罗方法预测的，远远高于室温。我们的发现揭示了FeTe ₂在2D磁性研究和自旋电子学应用中的广阔前景。