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The spin Hall magnetoresistance (SMR) effect is studied in a magnetoelectric Cr2O3/heavy-metal W heterostructure. The Cr2O3 film is confirmed as the α-phase, and its Néel temperature is determined. A clear SMR behavior is observed at the interface of Cr2O3/W. A nearly 0.1% SMR ratio is achieved under a magnetic field of 9 T, which is larger than the reported value in the SrMnO3/Pt structure. A systematic study on the variations of SMR as functions of the magnetic field and its angle is performed. Our results indicate that the antiferromagnetic magnetoelectric Cr2O3/W structure has a promising prospect application in future spintronic devices.

For prospective spintronics devices based on the propagation of pure spin currents, antiferromagnets are an interesting class of materials that potentially entail a number of advantages as compared to ferromagnets. Here, we present a detailed theoretical study of magnonic spin current transport in ferromagnetic-antiferromagnetic multilayers by using atomistic spin dynamics simulations.The relevant length scales of magnonic spin transport in antiferromagnets are determined. We demonstrate the transfer of angular momentum from a ferromagnet into an antiferromagnet due to the excitation of only one magnon branch in the antiferromagnet. As an experimental system, we ascertain the transport across an antiferromagnet in YIG|Ir 20 Mn 80 |Pt heterostructures. We determine the spin transport signals for spin currents generated in the YIG by the spin Seebeck effect and compare to measurements of the spin Hall magnetoresistance in the heterostructure stack. By means of temperature-dependent and thickness-dependent measurements, we deduce conclusions on the spin transport mechanism across IrMn and furthermore correlate it to its paramagnetic-antiferromagnetic phase transition. arXiv:1803.03416v1 [cond-mat.mtrl-sci]

Abstract:The direct reductive amination of carbonyl compounds with NH3 and H2 is an alternative route to produce primary amines in practical production. The search for efficient and selective catalysts has attracted great interest. In the present work, the reductive amination of heptaldehyde with NH3 was investigated over a Ru-based catalyst. The product selectivities were found to be related with the supports of Ru. The alumina with spinel structure (γ-Al2O3, θ-Al2O3)-supported Ru catalysts exhibited selectivity favoring primary amines (94% yield) at 100% heptaldehyde conversion under optimal conditions. Purely basic (MgO, CaO) and relative acidic (Nb2O5, SnO2, MCM-41, HZSM-5) supports showed relatively poor selectivity towards primary amines (0%-53% yield). The reductive amination mechanism was also proposed. The Schiff base N- [heptylene]heptyl-1-amine was a key intermediate. Ru/γ-Al2O3 was shown to be an excellent hydrogenolysis catalyst to selectively produce primary amine by amination and hydrogenolysis of N- [heptylene]heptyl-1-amine. OPEN ACCESSCatalysts 2015, 5 2259