Designed Metamagnetism in CoMnGe_{1-x}P_{x}

We extend our previous theoretical study of Mn-based orthorhombic metamagnets to those that possess large nearest neighbour Mn-Mn separations (d1>3.22A). Based on our calculations, we design and synthesize a series of alloys, CoMnGe_{1-x}P_{x}, to experimentally demonstrate the validity of the model. Unusually, we predict and prepare several metamagnets from two ferromagnetic end-members, thus demonstrating a new example of how to vary crystal structure, within the Pnma symmetry group, to provide highly tunable metamagnetism

Field Ion Microscopy of C_<60> Molecules(APFIM/FIM)

Field ion microscopy of C_ on the tungsten substrate showed that (1) the field ion image of the C_ adsorbate reflects the LUMO (lowest unoccupied molecular orbital)-induced local density of states of the C_, similar to the recent STM image of the C60 on the Cu(111)1 x 1 surface and that (2) the field evaporation occurs as a C_ molecule, in glaring contrast to the recent report by Ohmae et al

Recent Atom Probe Studies at IMR : a Comprehensive Review(APFIM/FIM)

This paper reviews our recent atom probe research activities conducted at Institute for Materials Research (IMR), Tohoku University, during a period of 1990 to date. The atom probe research started at IMR when the authors constructed an energy compensated time-of-flight atom probe in 1990. Since then, this instrument has been employed for various metallurgical problems, providing better understandings to mechanisms of microstructural evolution in various metallic materials. Notable achievements are studies of precipitation processes in aluminum alloys, nanocrystallization processes of amorphous alloys, microstructural characterizations of magnetic thin films and various other metallic materials. A new instrument equipped with a reflectron type time-of-flight atom probe and a position sensitive atom probe (PoSAP) was constructed in 1994. This instrument allowed three dimensional visualizations of atom distributions in alloys with an atomic resolution. PoSAP has been employed to characterize microstructures in Cr-Fe and Co-Cr(-Ta) magnetic alloys

Large amplitude microwave emission and reduced nonlinear phase noise in Co2Fe(Ge0.5Ga0.5) Heusler alloy based pseudo spin valve nanopillars

We have studied microwave emission from a current-perpendicular-to-plane pseudo spin valve nanopillars with Heusler alloy Co2Fe(Ga0.5Ge0.5) electrodes. Large emission amplitude exceeding 150 nV/Hz^0.5, partly owing to the large magnetoresistance, and narrow generation linewidth below 10 MHz are observed. We also find that the linewidth shows significant dependence on the applied field magnitude and its angle within the film plane. A minimum in the linewidth is observed when the slope of the frequency versus current becomes near zero. This agrees with theoretical prediction that takes into account non-linear phase noise as a source for linewidth broadening