Strongly Correlated Molecular Magnet with Curie Temperature above 60 K

Abstract

Molecular ferromagnet with the ordering temperature of 60 K was synthesized via template-based solution method and showed its capability in magnetic, optical, and electrical applications based on magnetic-dielectric coupling effect and photoirradiation-induced low-resistivity state. The approach shown here can be extended to a family of molecular magnets.

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

“…Research in 2D atomically crystalline magnets is rapidly expanding from solid-state preparation to exfoliation down to atomically thin units. ,, As for the already-synthesized 2D iron-tetracyanoquinodimethane (FeTCNQ) molecular magnet with dynamic control of magnetism and conductive states, we show that the monolayer derivative of this material has intrinsic electron spin polarization and stable ferromagnetism. Thanks to its strong and highly coordinated organic bonds, the pristine Fe 2 (TCNQ) 2 monolayer has significant in-plane Young’s modulus and Poisson’s ratio anisotropy.…”

“…Two-dimensional (2D) magnetism has long been at the heart of numerous theoretical, experimental, and technological advances, − such as the study of topology, the fluctuation-driven generation of new phases, and the electrical manipulation and detection of spin. A promising aspect of 2D magnetism is the ability to rapidly fabricate various 2D heterostructures with engineered levels of strain, chemistry, and optical and electrical properties. − Just as graphene revolutionized condensed matter and materials engineering, the introduction of a new class of 2D atomic crystals, magnetic van der Waals (vdW) materials, is expected to open up a wide range of possibilities for applications and fundamental research. − Indeed, the wide flexibility of 2D vdW magnetic atomic crystals with different elements, structures, and thicknesses suggests straightforward tuning of the magnetic anisotropy, ,,− which will lead to the biggest potential payoffs in the near future in relation to new physical phenomena and devices.…”

“…The rich quantum mechanical behavior displayed by this class of molecules has generated strong interest, and possible applications in fields such as high-density memory storage, spintronics, and quantum computing have all been envisioned. The 2D molecular magnet, one crucial member of the magnet family, whose magnetic phenomena, such as unique quantum effects and sensitivity to external stimuli, can manifest differently. ,− However, the creation of 2D molecular magnets can be obtained just by the molecular-based strategy, strictly, which makes 2D molecular magnets holy and attracts extensive attention.…”

“…It is clear that the Fe 2 (TCNQ) 2 monolayer has sharp peaks at 2θ = 8.96°, 13.46°, 15.59°, 18.02°, 22.53°, and 27.11°, corresponding to their (002), (003), ( 201), (004), (005), and (006) planes as shown in Figure 2b. However, compared with the alreadysynthesized FeTCNQ network, 11 those sharp peaks have tendencies to deflect to smaller angles, which can be regarded as fingerprints to identify the Fe 2 (TCNQ) 2 framework from its bulk network.…”

“…The ground state of the Fe 2 (TCNQ) 2 monolayer maintains the ferromagnetic (FM) order as the layered FeTCNQ network, 11 with a magnetic moment of 4 μ B per unit cell, which is 0.22 eV lower than the antiferromagnetic state. To visualize the spatial distribution of spins in the Fe 2 (TCNQ) 2 lattice, we plotted the spin-polarized electron densities Δρ, which is calculated from the difference between electron densities of two spin channels: Δρ = ρ ↑ − ρ ↓ , as shown in Figure 3b.…”