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2D magnetic materials with dimerized honeycomb lattices can be treated as mixed‐spin square lattices, in which a quantum phase transition may occur to realize the Bose–Einstein condensation of magnons under reachable experimental conditions. However, this has never been successfully realized with integer spin centers. Herein, a spin integer (S = 2) dimerized honeycomb lattice in an iron(II)‐azido compound [Fe(4‐etpy)2(N3)2]n (FEN, 4‐etpy = 4‐ethylpyridine) is realized. Morphology characterization by transmission electron microscopy, scanning electron microscopy, and atomic force microscopy spectroscopies show that the thinnest place of the sample is ≈13 nm, which is equal to ten layers of the compound. In contrast to the common magnetic properties of long‐range magnetic ordering, Mössbauer and polarized neutron scattering studies reveal that FEN exhibits a reentrant spin glass behavior owing to competing ferro‐ and antiferromagnetic exchange‐coupling interactions within the lattice. Two spin glass phases with disparate canting angles are characterized at 39 and 28 K, respectively. By using Curély's model, two exchange‐coupling constants (J1 = +35.8 cm−1 and J2 = −3.7 cm−1) can be simulated. Moreover, a very large coercive field of ≈1.9 Tesla is observed at 2 K, making FEN a "very hard" van der Waals 2D magnetic material. [ABSTRACT FROM AUTHOR]

Thermal interface materials with high thermal conductivity and low hardness are crucial to the heat dissipation of high-power electronics. In this study, a high magnetic field was used to align the milled carbon fibers (CFs, 150 μm) in silicone rubber matrix to fabricate thermal interface materials with an ordered and discontinuous structure. The relationship among the magnetic field density, the alignment degree of CFs, and the properties of the resulting composites was explored by experimental study and theoretical analysis. The results showed higher alignment degree and enhanced thermal conductivity of composites under increased magnetic flux density within a certain curing time. When the magnetic flux density increased to 9 T, the CFs showed perfect alignment and the composite showed a high thermal conductivity of 11.76 W/(m·K) with only 20 vol% CF loading, owing to the ordered structure. Meanwhile, due to the low filler loading and discontinuous structure, a low hardness of 60~70 (shore 00) was also realized. Their thermal management performance was further confirmed in a test system, revealing promising applications for magnetic aligned CF–rubber composites in thermal interface materials. [ABSTRACT FROM AUTHOR]

2D Frustrated Magnets: Reentrant Spin Glass and Large Coercive Field Observed in a Spin Integer Dimerized Honeycomb Lattice (Adv. Funct. Keywords: 2D frustrated magnets; dimerized honeycomb lattices; iron(II); neutron scattering; spin glass EN 2D frustrated magnets dimerized honeycomb lattices iron(II) neutron scattering spin glass 1 1 1 01/06/21 20210104 NES 210104 In article number 2004744, Zhendong Fu, Yan-Zhen Zheng, and co-workers report a van der Waals 2D magnetic material bearing a spin-integer dimerized honeycomb lattice. 2D frustrated magnets, dimerized honeycomb lattices, iron(II), neutron scattering, spin glass. [Extracted from the article]

The triangular-lattice spin liquid (QSL) candidate NaYbO 2 is magnetically diluted by Lu doping, forming homogeneous solid solutions NaYb 1- x Lu x O 2 (0≤ x <1.0). A combination of structural, magnetic, and pulsed high-field electron spin resonance analysis shows that the lattice parameters and the Curie-Weiss temperature θ CW vary almost linearly with x , and the crystal electric field environment of the Yb/Lu ions persists during the Lu doping. The statistical distribution analysis of clusters and the deduced linear θ CW ∼ x relation indicate that the nearest neighbor exchange J does not change with magnetic dilution. Interestingly, with the magnetization measurement at 0.39 K, we have observed S eff = 1/2 antiferromagnetic Yb-Yb dimers in NaYb 0.02 Lu 0.98 O 2 , which is manifested as a magnetization step at μ 0 H c = 2.68 T due to the transition between singlet and triplet states. Thus, the intradimer interaction is directly determined as J / k B = −5.15 K. Surprisingly, this value is close to the interaction of undoped NaYbO 2 , supporting the theoretical analysis of clusters. Our study provides a method of estimating the magnetic interaction of QSL materials through magnetic dilution. The statistical distribution analysis of magnetic clusters suggests that through a small amount of Lu doping (x < 0.5), the QSL state in NaYbO 2 can continue to be maintained. • The triangular-lattice spin liquid material NaYbO 2 is magnetically diluted by Lu doping, forming homogeneous solid solutions NaYb 1- x Lu x O 2 (0≤ x <1.0). • We have observed the magnetic dimers in x = 0.98 by the M (H) curve at 0.39 K. Thus, the intradimer interaction is directly determined as J / k B = −5.15 K, which is close to the interaction of undoped NaYbO 2. [ABSTRACT FROM AUTHOR]