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Magnetic force microscopy (MFM) observations have been performed on artificial structures of single-phase Ga0.962Mn0.038N grown by metal organic chemical vapor deposition, showing room-temperature long range magnetic order of Ga0.962Mn0.038N. The MFM results agree well with the theoretical simulation under assumption of uniform magnetization. The ferromagnetism of Ga1-xMnxN is suggested to be closely related to the configuration of Mnn+ and Mn(n+1)+ (n=2,3). This work indicates potential of effectively applying MFM to a variety of weak magnetic epitaxial thin films. [ABSTRACT FROM AUTHOR]

We report an unusual transition from a locally ductile to a pure brittle fracture in the dynamic fracture of brittle Mg65Cu20Gd10 bulk metallic glass. The fractographic evolution from a dimple structure to a periodic corrugation pattern and then to the mirror zone along the crack propagation direction during the dynamic fracture process is discussed within the framework of the meniscus instability of the fracture process zone. This work might provide an important clue in understanding of the energy dissipation mechanism for dynamic crack propagation in brittle glassy materials. [ABSTRACT FROM AUTHOR]

Magnetic aftereffect and surface magnetic domain structure of (Fe0.675Pt0.325)100-xBx(x=12–20) nanocomposites have been investigated for correlating with their corresponding phases and magnetic properties. Exchange-coupling effect between grains is present for all the studied ribbons as evidenced by Henkel plot. The volume fraction of magnetically soft phases decreases with increasing B concentration from x=12 to x=18. It leads to the reduction in the activation volume of the reverse domain. Among all samples, the (Fe0.675Pt0.325)82B18 ribbon having the highest intrinsic coercivity (iHc) exhibits minimum value in activation volume V=1.1×10-18 cm3, because it possesses the least volume fraction of the magnetic soft phases, i.e., Fe2B or Fe3B phases. Magnetic force microscopy studies reveal the magnetic domain structures of the ribbons, confirming the existence of strong exchange coupling between magnetic grains. [ABSTRACT FROM AUTHOR]

We have investigated the magnetization reversal process of the disk-, ring-, and center dot ring-patterned Ni[SUB80]Fe[SUB20] wires. For the fields applied perpendicular to the wire direction, interesting shape dependent magnetoresistance (MR) ratios were found. The MR ratios were varied from 0.8%, 0.65%, and 0.4% at room temperature and 1.7%, 1.5%, and 1.1% at 10 K for the disk-, ring-, and center dot ring-patterned wires. For the same wires, the switching field is reduced from -170, -110, and -90 Oe at room temperature to -140, -70, and -20 Oe at 10 K. These results were due to the shape anisotropy and domain-wall motion. The anisotropy MR (AMR) ratios measured at 10 K of the disk-, ring-, and center dot ring-patterned wires were 1.9 ± 0.1%, 1.7 ± 0.1%, and 1.3 ± 0.1%, respectively, it is almost even the same (1.1 ± 0.1%) at room temperature. We have observed that the center dot reduces the MR ratio and increases magnetic saturation field of the Ni[SUB80]Fe[SUB20] wires. [ABSTRACT FROM AUTHOR]

The King AbdulAziz City for Science & Technology in the Kingdom of Saudi Arabia plans to build a 10MeV, 15kW linear accelerator (LINAC) for electron beam and X-ray. The accelerator will be supplied by EB Tech, Republic of Korea, and the design and construction of the accelerator building will be conducted in the cooperation with EB Tech. This report presents the shielding analysis of the accelerator building using the Monte Carlo N-Particle Transport Code (MCNP). In order to improve the accuracy in estimating deep radiation penetration and to reduce computation time, various variance reduction techniques, including the weight window (WW) method, the deterministic transport (DXTRAN) spheres were considered. Radiation levels were estimated at selected locations in the shielding facility running MCNP6 for particle histories up to 1.0×10+8. The final results indicated that the calculated doses at all selected detector locations met the dose requirement of 50 mSv/yr, which is the United State Nuclear Regulatory Commission (U.S. NRC) requirement. [ABSTRACT FROM AUTHOR]