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Thin films of lithium spinel ferrite, LiFe5O8, have attracted much scientific attention because of their potential for efficient excitation, the manipulation and propagation of spin currents due to their insulating character, high-saturation magnetization, and Curie temperature, as well as their ultra-low damping value. In addition, LiFe5O8 is currently one of the most interesting materials in terms of developing spintronic devices based on the ionic control of magnetism, for which it is crucial to control the lithium's atomic content. In this work, we demonstrate that dual ion beam sputtering is a suitable technique to tailor the lithium content of thin films of lithium ferrite (LFO) by using the different energies of the assisting ion beam formed by Ar+ and O2+ ions during the growth process. Without assistance, a disordered rock-salt LFO phase (i.e., LiFeO2) can be identified as the principal phase. Under beam assistance, highly out-of-plane-oriented (111) thin LFO films have been obtained on (0001) Al2O3 substrates with a disordered spinel structure as the main phase and with lithium concentrations higher and lower than the stoichiometric spinel phase, i.e., LiFe5O8. After post-annealing of the films at 1025 K, a highly ordered ferromagnetic spinel LFO phase was found when the lithium concentration was higher than the stoichiometric value. With lower lithium contents, the antiferromagnetic hematite (α-Fe2O3) phase emerged and coexisted in films with the ferromagnetic LixFe6-xO8. These results open up the possibility of controlling the properties of thin lithium ferrite-based films to enable their use in advanced spintronic devices. [ABSTRACT FROM AUTHOR]

High-density Ag nanotwinned films with a very thin twin spacing of about 6.05 nm have been deposited by electron beam evaporation for the first time. With ion beam assistance, Ag thin films with a highly <111> textured structure can be deposited on Si substrates pre-coated with Ti/Ag (111) seed layers. In contrast, the Ag films deposited without ion beam assistance exhibit mostly fine grains with about 0.8 μm grain size and random annealing twins. The nanotwinned Ag films have a nanoindentation hardness of 1.23 GPa, about five times higher than that of Ag films deposited without ion beam assistance. For the mechanism of enhancing nanotwin formation in Ag films deposited with ion beam assistance, the energy and stress perspectives are both discussed. The formation of Ag nanotwins is ascribed to sufficient stress induced by ion bombardment under suitable parameters, which leads to the generation of twinning partial dislocations, formation of twin boundaries, and release of strain energy. [ABSTRACT FROM AUTHOR]