Spin-Gapless States in Two-Dimensional Molecular Ferromagnet Fe₂(TCNQ)₂

Abstract

Two-dimensional van der Waals magnetic atomic crystals have provided unprecedented access to magnetic ground states due to a quantum confinement effect. Here, using first-principles calculations, we demonstrate a spin-gapless molecular ferromagnet, namely, Fe2(TCNQ)2, with superior mechanical stability and a remarkable linear Dirac cone, which can be exfoliated from its already-synthesized van der Waals crystal. Especially, Young’s modulus has values of 175.28 GPa·nm along the x- and y-directions with a Poisson’s ratio of 0.29, while the Curie temperature within the Ising model is considerably higher than room temperature. Furthermore, spin–orbit coupling can open a band gap at the Dirac point, leading to topologically nontrivial electronic states characterized by an integer value of the Chern number and the edge states of its nanoribbon. Our results offer versatile platforms for achieving plastic spin filtering or a quantum anomalous Hall effect with promising applications in spintronics devices.

Unravelling abnormal in-plane stretchability of two-dimensional metal–organic frameworks by machine learning potential molecular dynamics

“…S8 †. The resulting difference of 0.72 (0.14 along the Γ–X direction and 0.86 along the Γ–M direction) is considerably larger than those reported for other systems including tetraoxa[8]circulene-based COFs (0.04–0.384), 48 Fe 2 (TCNQ) 2 MOF (0.41), 49 and M 3 (C 6 X 6 ) 2 (M = Co, Cr, Cu, Fe, Mn, Ni, Pd, Rh and X = O, S, Se) MOF (0–0.04), 50 that highlight an ultra-high in-plane flexibility of 2D NiF 2 (pyz) 2 . Such ultra-high in-plane Poisson's ratio combined with high anisotropy makes 2D NiF 2 (pyz) 2 a good candidate for practical large-magnitude strain engineering.…”

Self-assembled molecular nanowires on prepatterned Ge(001) surfaces

“…TCNQ molecules, as archetypal electron acceptors, are widely utilized to prepare charge transfer complexes, showing potential in engineering molecular electronics. [31][32][33][34] The electronic properties of TCNQ are mainly determined by the population of the lowest unoccupied molecular orbital (LUMO) (Fig. 1f).…”

Mini-review of interesting properties in Mn2CoAl bulk and films

“…In 2018, Zhang et al (2018) proposed the nodal ring spin-gapless semiconducting state in a 2D HK lattice via first-principle calculations. In 2022, Ding et al (2022) summarized almost all the predicted nodal ring/line spin-gapless semiconductors in 2D and 3D materials ( Guan et al, 2013 ; Li and Yang, 2013 ; Ding and Wang, 2015 ; Wang et al, 2016b ; Rasool et al, 2016 ; Wang et al, 2017c ; Liu et al, 2017 ; Deng et al, 2018b ; Wang et al, 2018 ; Huang et al, 2019b ; Wu et al, 2020b ; Guo et al, 2020 ; Li et al, 2021 ; Wang et al, 2021 ; Ji et al, 2022 ; Wu et al, 2022 ) in the past 3 years. Remarkably, they ( Ding et al, 2022 ) also provided three valuable suggestions for the future theoretical design of nodal ring/line spin-gapless semiconductors.…”