We report a strong size dependence of coercivity in amorphous ferrimagnetic
TbFeCo films. The as-deposited film exhibited a low saturation magnetization
(Ms=100 emu/cc) and a high perpendicular anisotropy (Ku=10^6 erg/cc). Hall-bar
devices were fabricated for characterizing the magneto-transport behaviors. A
significant increase in coercivity (up to 300 %) was observed at room
temperature as the width of Hall bar was reduced. The large coercivity
enhancement was attributed to the relaxation of film stress. The effect of
strain and dimensionality on the coercivity in TbFeCo makes it attractive for
tunable coercivity and the magnetization reversal in future nanoscale devices.Comment: 17 pages, 3 figure
Epitaxial L1 0 MnAl films demonstrated two different kinds of magneto-transport behaviors as a function of temperature. The magneto-resistance ratio (MR) was negative and exhibited evident enhancement in the resistivity at coercive fields above ~175 K. The MR enhancement was attributed to the increase of the magnetic domain walls based on the quantitative correlation between the domain density and the resistivity. Below 175 K, the MR was positive and showed a quadratic dependence on the external magnetic field, which implied that the MR was dominated by Lorentz effects below 175 K.
One of many challenges for niobium (Nb) based superconducting devices is the improvement over the surface morphology and superconducting properties as well as the reduction of defects. We employed a novel deposition technique, i.e. biased target ion beam deposition technique (BTIBD) to prepare Nb thin films with controlled crystallinity and surface morphology. We found that the target current (I Target ) and the target bias (V Target ) were critical to the crystallinity and surface morphology of Nb films. The high target current (I Target >500 mA and V Target = 400 V bias) during the deposition degraded the Nb crystallinity, and subsequently reduced the critical temperature for superconductivity (T c ). V Target was critical to the surface morphology, i.e. grain size and shape and the surface roughness. The optimized growth condition yielded very smooth film with RMS roughness of 0.4 nm that was an order of magnitude smoother than that of Nb films by sputtering process. The critical temperature for superconductivity was also close to the value of the bulk Nb. The quality of Nb film was evident in the presence of a very thin proximity layer (~ 0.8 nm). The experimental results demonstrated that the preparation of smooth Nb films with adequate superconductivity by BTIBD could serve as a base electrode for the in-situ magnetic layer or insulating layer for superconducting electronic devices.
Epitaxial MnAl films with a high chemical ordering were synthesized and characterized during a series of irradiations by 2 MeV protons (H þ ). The chemical ordering was first reduced to a minimum at a total fluence (TF) of 1 Â 10 15 H þ /cm 2 , and consequently was recovered at the final total fluence of 2 Â 10 15 H þ /cm 2 . We attributed the recovery of chemical ordering to thermal effects and the enhanced diffusion caused by the high energy protons. In addition, the damages by the protons have little effect on the magnetic scattering processing in MnAl characterized by the anomalous Hall effect. V C 2013 American Institute of Physics. [http://dx.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.