The recent discovery of magnetism within the family of exfoliatable van der Waals (vdW) compounds has attracted considerable interest in these materials for both fundamental research and technological applications. However, current vdW magnets are limited by their extreme sensitivity to air, low ordering temperatures, and poor charge transport properties. Here the magnetic and electronic properties of CrSBr are reported, an air‐stable vdW antiferromagnetic semiconductor that readily cleaves perpendicular to the stacking axis. Below its Néel temperature, TN = 132 ± 1 K, CrSBr adopts an A‐type antiferromagnetic structure with each individual layer ferromagnetically ordered internally and the layers coupled antiferromagnetically along the stacking direction. Scanning tunneling spectroscopy and photoluminescence (PL) reveal that the electronic gap is ΔE = 1.5 ± 0.2 eV with a corresponding PL peak centered at 1.25 ± 0.07 eV. Using magnetotransport measurements, strong coupling between magnetic order and transport properties in CrSBr is demonstrated, leading to a large negative magnetoresistance response that is unique among vdW materials. These findings establish CrSBr as a promising material platform for increasing the applicability of vdW magnets to the field of spin‐based electronics.

The recent discovery of two-dimensional (2D) magnets [1][2][3] offers unique opportunities for the experimental exploration of low-dimensional magnetism 4 and the magnetic proximity effects 5,6 , and for the development of novel magnetoelectric, magnetooptic and spintronic devices 7,8 . These advancements call for 2D materials with diverse magnetic structures as well as effective probes for their magnetic symmetries, which is key to understanding intralayer magnetic order and interlayer magnetic coupling [9][10][11] . However, traditional techniques do not probe magnetic symmetry; these examples include magneto-optical Kerr effect 2,3 , reflective magnetic circular dichroism and Raman spectroscopy [12][13][14] , anomalous Hall effect 15 , tunneling magnetoresistance 16,17 , spin-polarized scanning tunneling microscopy 9 , and single-spin scanning magnetometry 18 . Here we apply second harmonic generation (SHG), a technique acutely sensitive to symmetry breaking, to probe the magnetic structure of a new 2D magnetic semiconductor, CrSBr. We find that CrSBr monolayers are ferromagnetically ordered below 146 K, an observation enabled by the discovery of a giant magnetic dipole SHG effect in the centrosymmetric 2D structure. In multilayers, the ferromagnetic monolayers are coupled antiferromagnetically, with the Néel temperature notably increasing with decreasing layer number. The magnetic structure of CrSBr, comprising spins co-aligned in-plane with rectangular unit cell, differs markedly from the prototypical 2D hexagonal magnets CrI3 and Cr2Ge2Te6 with out-of-plane moments.

When monolayers of two-dimensional (2D) materials are stacked into van der Waals structures, interlayer electronic coupling can introduce entirely new properties, as exemplified by recent discoveries of moiré bands that host highly correlated electronic states and quantum dot-like interlayer exciton lattices. Here we show the magnetic control of interlayer electronic coupling, as manifested in tunable excitonic transitions, in an A-type

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The emergence of two-dimensional (2D) magnetic crystals and moiré engineering of van der Waals materials has opened the door for devising new magnetic ground states via competing interactions in moiré superlattices 1-9 . Although a suite of interesting phenomena, including multi-flavor magnetic states 10 , noncollinear magnetic states 10-13 , moiré magnon bands and magnon networks 14 , has been predicted in twisted bilayer magnetic crystals, nontrivial magnetic ground states have yet to be realized. Here, by utilizing the stacking-dependent interlayer exchange interactions in CrI3 (Ref. 15, 16 ), we demonstrate in small-twist-angle CrI3 bilayers a noncollinear magnetic ground state. It consists of antiferromagnetic (AF) and ferromagnetic (FM) domains and is a result of the competing interlayer AF coupling in the monoclinic stacking regions of the moiré superlattice and the energy cost for forming AF-FM domain walls. Above a critical twist angle of ~ 𝟑°, the noncollinear state transitions to a collinear FM ground state. We further show that the noncollinear magnetic state can be controlled by electrical gating through the doping-dependent interlayer AF interaction. Our results demonstrate the possibility of engineering new magnetic ground states in twisted bilayer magnetic crystals, as well as gate-voltage-controllable high-density magnetic memory storage.Moiré superlattices built on twisted bilayers of van der Waals materials have presented an exciting platform for studying correlated states of matter with unprecedented controllability [7][8][9] . In addition to graphene and transition metal dichalcogenide moiré materials 17 , recent theoretical studies have predicted the emergence of new magnetic ground states in twisted bilayers of 2D magnetic crystals [10][11][12][13][14] . These states are originated from the stacking-dependent interlayer exchange interactions in magnetic moiré superlattices. Two-dimensional CrI3 (similarly CrBr3 18 and CrCl3 19 ), in which stackingdependent interlayer magnetic ground states have been demonstrated by recent experiments 15, 16 , is a good candidate for exploring moiré magnetism.

The design and development of metal-cluster-based heterogeneous catalysts with high activity, selectivity, and stability under solution-phase reaction conditions will enable their applications as recyclable catalysts in large-scale fine chemicals production. To achieve these required catalytic properties, a heterogeneous catalyst must contain specific catalytically active species in high concentration, and the active species must be stabilized on a solid catalyst support under solution-phase reaction conditions. These requirements pose a great challenge for catalysis research to design metal-cluster-based catalysts for solution-phase catalytic processes. Here, we focus on a silica-supported, polymer-encapsulated Pt catalyst for an electrophilic hydroalkoxylation reaction in toluene, which exhibits superior selectivity and stability against leaching under mild reaction conditions. We unveil the key factors leading to the observed superior catalytic performance by combining X-ray absorption spectroscopy (XAS) and reaction kinetic studies. On the basis of the mechanistic understandings obtained in this work, we also provide useful guidelines for designing metal-cluster-based catalyst for a broader range of reactions in the solution phase.

A switchable water-adhesive, super-hydrophobic nanowire surface is developed for the formation of functional stem cell spheroids. The sizes of hADSC spheroids are readily controllable on the surface. Our surface increases cell-cell and cell-matrix interaction, which improves viability and paracrine secretion of the spheroids. Accordingly, the hADSC spheroids produced on the surface exhibit significantly enhanced angiogenic efficacy.

Most chemical processes are basically multiple input/ multiple output (MIMO) systems. Despite considerable work on advanced multivariable controllers for MIMO systems, multiloop proportional-integral-derivative (PID) controllers remain the standard for many industries because of their adequate performance with most simple, failure tolerant, and easy to understand structure. In a multiloop system, once a control structure is fixed, control performance is then determined mainly by tuning each multiple single-loop PID controller. However, because the interactions that exist between the control loops make the proper tuning of the multiloop PID controllers quite difficult, only a relatively few tuning methods are available to the multiloop PID controllers and most of them require nonanalytical forms with complex iterative steps (Loh et al., 1993;Luyben, 1986;Skogestad and Morari, 1989). The analytical tuning rule is very attractive, with respect to its practicality, but the mathematical complexity attributed to the loop interactions has mainly prevented the analytical approach to the multiloop systems.In this article, we propose an analytical design method for the multiloop PID controllers to give desired closed-loop responses by extending the generalized IMC-PID method for single input/single output (SISO) systems (Lee et al., 1998) to MIMO systems. Simple but efficient tuning rules are obtained for general process models by using the frequency-dependent property of the closed-loop interactions. Theory Direct extension of generalized IMC-PID method to multiloop systems and its limitationIn the multiloop feedback system, shown in Figure 1, the closed-loop transfer function matrix H(s) is given bywhere G(s) is the open-loop stable process, K (s) is the multiloop controller, and y(s) and r(s) are the controlled variable vector and the set-point vector, respectively. According to the design strategy of the multiloop IMC controller (Economou and Morari, 1986), the desired closedloop response R i of the ith loop is typically chosen bywhere G iiϩ is the nonminimum part of G ii and is chosen to be the all-pass form, i is an adjustable constant for system performance and stability, and n i is chosen such that the IMC controller would be realizable. The requirement of G iiϩ (0) ϭ 1 is necessary for the controlled variable to track its set point. Let the desired closed-loop response matrix R (s) be R ͑s͒ ϭ diag͓R 1 , R 2 , . . . , R n ͔