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Consolidation of pure molybdenum through laser powder bed fusion and other additive manufacturing techniques is complicated by a high melting temperature, thermal conductivity and ductile-to-brittle transition temperature. Nano-sized SiC particles (0.1 wt%) were homogeneously mixed with molybdenum powder and the printing characteristics, chemical composition, microstructure, mechanical properties were compared to pure molybdenum for scan speeds of 100, 200, 400, and 800 mm/s. The addition of SiC improved the optically determined density and flexural strength at 400 mm/s by 92% and 80%, respectively. The oxygen content was reduced by an average of 52% over the four scan speeds analyzed. Two mechanisms of oxygen reduction were identified as responsible for the improvements: oxidation of free carbon and the creation of secondary phase nanoparticles. This study illustrates the promising influence of nanoparticle additions to refractory metals in laser powder bed fusion.

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Realization of the quantum anomalous Hall (QAH) effect has been demonstrated in several magnetic topological insulators (MTIs). MTIs can be synthesized by doping magnetic elements into topological insulators (TIs) [1][2][3][4][5][6][7][8][9] or growth of intrinsic MTI compounds. [10][11][12][13][14][15][16][17][18][19] However, these MTI materials require temperatures much lower than their magnetic T c to achieve quantization in the Hall effect. This deficiency has been attributed to inhomogeneity in magnetic doping which causes localized variation in surface state exchange gaps. Magnetism can also be induced in the surface of TI thin films via proximity exchange effect. This proximity induced magnetization (PIM) is envisioned by coupling TIs with a magnetic insulator (MI). PIM in TIs have been experimentally confirmed in heterostructures of TIs with magnetic insulators (MIs) such as rare earth garnets and EuS, [20][21][22][23][24][25][26][27][28] MTIs, [29,30] and telluride van der Waals (vdW) magnets. [31] However, recent studies have pointed out the complexities in measuring proximity exchange in these systems, [31] which can be affected by a number of problems such as diffusion at the interface and band bending. Thus, providing a barrier for diffusion while permitting magnetic exchange in TI/MI heterostructures will be necessary for devices, and it is shown here that a TiO x interface barrier achieves this goal. Only a single study by Watanabe et al. [31] has shown PIM and QAH in a TI/MI/TI thin film sandwich structure of (Zn,Cr)Te/(Bi,Sb) 2 Te 3 /(Zn,Cr)Te. However, even in this material system, the QAH effect was seen at extremely low temperature of 0.03 K. This low temperature is possibly due to: (1) High-quality MIs which were grown on TI thin films have very low Curie temperature, T c , such as (Zn,Cr) Te with T c < 40 K [31] and EuS with T c of ≈17 K. [25] (2) Even with 20-25% of the magnetic species, Cr in (Zn,Cr)Te, finite localized nonmagnetic nanoregions may exist in the samples.MIs such as rare-earth garnets and ferrites are excellent materials that are magnetically ordered well above room-temperature, making them ideal candidates for QAH materials coupled with TIs. However, growth of MIs on top of TIs using Combining topological insulators (TIs) and magnetic materials in heterostructures is crucial for advancing spin-based electronics. Magnetic insulators (MIs) can be deposited on TIs using the spin-spray process, which is a unique nonvacuum, low-temperature growth process. TIs have highly reactive surfaces that oxidize upon exposure to atmosphere, making it challenging to grow spinspray ferrites on TIs. In this work, it is demonstrated that a thin titanium capping layer on TI, followed by oxidation in atmosphere to produce a thin TiO x interfacial layer, protects the TI surface, without significantly compromising spin transport from the magnetic material across the TiO x to the TI surface states. First, it is demonstrated that in Bi 2 Te 3 /TiO x /Ni 80 Fe 20 heterostructures, TiO x provides an e...

LHPG method is used to grow high optical quality single crystal fibers. For LHPG, polycrystalline ceramics can play important roles as feedstocks and cladding on the single crystal fibers.

Ultra-thin films of low damping ferromagnetic insulators with perpendicular magnetic anisotropy have been identified as critical to advancing spin-based electronics by significantly reducing the threshold for current-induced magnetization switching while enabling new types of hybrid structures or devices. Here, we have developed a new class of ultra-thin spinel structure Li0.5Al1.0Fe1.5O4 (LAFO) films on MgGa2O4 (MGO) substrates with: 1) perpendicular magnetic anisotropy; 2) low magnetic damping and 3) the absence of degraded or magnetic dead layers. These films have been integrated with epitaxial Pt spin source layers to demonstrate record low magnetization switching currents and high spin-orbit torque efficiencies. These LAFO films on MGO thus combine all of the desirable properties of ferromagnetic insulators with perpendicular magnetic anisotropy, opening new possibilities for spin based electronics.