Magnetic and defect probes of the SmB6 surface state

The impact of nonmagnetic and magnetic impurities on topological insulators is a central focus concerning their fundamental physics and possible spintronics and quantum computing applications. Combining scanning tunneling spectroscopy with transport measurements, we investigate, both locally and globally, the effect of nonmagnetic and magnetic substituents in SmB₆, a predicted topological Kondo insulator. Around the so-introduced substitutents and in accord with theoretical predictions, the surface states are locally suppressed with different length scales depending on the substituent's magnetic properties. For sufficiently high substituent concentrations, these states are globally destroyed. Similarly, using a magnetic tip in tunneling spectroscopy also resulted in largely suppressed surface states. Hence, a destruction of the surface states is always observed close to atoms with substantial magnetic moment. This points to the topological nature of the surface states in SmB₆ and illustrates how magnetic impurities destroy the surface states from microscopic to macroscopic length scales.

Versatile Coordination Modes of Multidentate Neutral Amine Ligands with Group 1 Metal Cations

This work comprehensively investigated the coordination chemistry of a hexa-dentate neutral amine ligand, namely, N,N',N"-tris-(2-N-diethylaminoethyl)-1,4,7-triaza-cyclononane (DETAN), with group-1 metal cations (Li+, Na+, K+, Rb+, Cs+). Versatile coordination modes were observed, from four-coordinate trigonal pyramidal to six-coordinate trigonal prismatic, depending on the metal ionic radii and metal's substituent. For comparison, the coordination chemistry of a tetra-dentate tris-[2-(dimethylamino)ethyl]amine (Me6Tren) ligand was also studied. This work defines the available coordination modes of two multidentate amine ligands (DETAN and Me6Tren), guiding future applications of these ligands for pursuing highly reactive and elusive s-block and rare-earth metal complexes.

Fabrication and evaluation of complicated microstructures on cylindrical surface

Various items of roll molds are popularly used to fabricate different kinds of optical films for optoelectronic information and other new and high-tech fields, while the fabrication and evaluation of optical microstructures on a cylindrical roller surface is more difficult than ecumenically manufactured products. In this study, the machinability of microstructures on the roll based on a fast tool servo (FTS) system is investigated. First, the flexible hinge holder for a FTS is designed and its structural parameters are optimized with finite-element analysis and fatigue reliability theory. The tool radius compensation algorithm for complicated microstructures is then deduced based on the surface fitting and bilinear interpolation algorithm of discrete data. Meanwhile, the evaluation index and method are proposed by the medium section method. Finally, a machining test of aspheric arrays on a cylindrical aluminum surface is carried out, and the high quality of the microstructure indicates that the proposed method is able to be used to fabricate optical microstructures.

Vermicular Eutectic Multi-Principal Element Alloy with Exceptional Strength and Ductility

Eutectic multi-principal element alloys (EMPEAs), with multiple main elements in compositions and eutectic microstructures, are considered promising high-performance materials for structural applications. The microstructure of EMPEAs usually exhibits a mixture of soft and hard phases in straight rod-like or lamellar morphology, which contribute to a balanced synergy of strength and ductility. However, such conventional morphology may also constrain the possible space for further improving their mechanical properties, and the question proposed is whether the straight morphology can be kinked to unlock a new space for achieving better mechanical properties. Here an (AlCrFe2)65Ni35 EMPEA featuring an unseen kinked vermicular eutectic microstructure is successfully prepared. This innovative microstructure imparts remarkably improved strength-ductility synergy to the EMPEA, which surpasses both its coarse-grained counterpart and typical EMPEAs with straight morphologies, indicating a pronounced strengthening of the vermicular eutectic microstructure. The phase-field simulation reveals the formation of such microstructure as the lack of crystallographic locking caused by the similar elastic modulus of the two eutectic phases. The findings not only expand the family of possible eutectic microstructures but also offer a pioneering paradigm for enhancing EMPEAs, paving the way for their application in high-performance structural materials.