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In this work, we report the influence of chemical substitution of Ni site by Cu, magnetic field of 50 kOe, and external pressure effect on martensite and intermartensite transformations in Ni49-xCuxMn38Sn13 (0.5≤x≤2) Heusler alloys. The substitution of Cu for Ni decreases the lattice parameter and introduces the intermartensitic transformation in this alloy series. Further, the intermartensitic transformation vanishes for higher Cu content (x1/42). The application of external magnetic field and hydrostatic pressure suppresses the intermartensitic transformation in Ni49-xCuxMn38Sn13 (0.5≤x≤1.5) and Ni49-xCuxMn38Sn13 (x=0.5) alloys, respectively. Also, the external magnetic field favors the stabilization of austenite phase while the external hydrostatic pressure favors the martensite phase. [ABSTRACT FROM AUTHOR]

A remarkably high saturation magnetization of ∼0.4μB/Fe along with room temperature ferromagnetic hysteresis loop has been observed in nanoscale (4–40 nm) multiferroic BiFeO3 which in bulk form exhibits weak magnetization (∼0.02μB/Fe) and an antiferromagnetic order. The magnetic hysteresis loops exhibit exchange bias and vertical asymmetry which could be because of spin pinning at the boundaries between ferromagnetic and antiferromagnetic domains. Interestingly, both the calorimetric and dielectric permittivity data in nanoscale BiFeO3 exhibit characteristic features at the magnetic transition point. These features establish the formation of a true ferromagnetic-ferroelectric system with a coupling between the respective order parameters in nanoscale BiFeO3. [ABSTRACT FROM AUTHOR]

A novel surface-emitting semiconductor laser with a vertical resonator, extremely short gain length, and enhanced gain at a specific design wavelength has been demonstrated. The gain medium consists of a series of GaAs quantum wells separated by AlGaAs spacers whose thicknesses are chosen to be one-half the wavelength of a particular transition in the quantum wells. This structure forces the antinodes of the standing-wave optical field to coincide with the gain elements, enhancing the gain and frequency selectivity in the vertical direction and substantially reducing amplified spontaneous emission. We have achieved optically pumped lasing with a threshold of 6 MW/cm2 at room temperature in a molecular beam epitaxially grown structure of thickness 4.3 μm, of which only 320 nm provided gain. [ABSTRACT FROM AUTHOR]

We report experimental studies of laser-induced degradation of surface photoluminescence efficiency in n-GaAs, p-GaAs, semi-insulating Cr-doped, and undoped liquid-encapsulated Czochralski-grown GaAs for excitation intensities ranging from ∼0.1 to ∼20 kW/cm2. The data suggest a contribution from optically induced defects in the bulk material. The time dependence of photoluminescence efficiency was fitted to a simple power-law expression. A previously unreported fast decay of photoluminescence, occurring in 1–2 s immediately following the cleaving of a fresh surface, was observed in p- and n-type samples. [ABSTRACT FROM AUTHOR]

Responds to comments made by Daniel Guidotti and Harold J. Hovel on the article 'Laser-induced degradation of GaAs photoluminescence,' published in the periodical 'Applied Physics Letters.' Experimental observations on high- and low-resistivity GaAs; Surface recombination-enhanced defect reaction model.

A remarkably high saturation magnetization of ∼0.4μB/Fe along with room temperature ferromagnetic hysteresis loop has been observed in nanoscale (4–40 nm) multiferroic BiFeO3 which in bulk form exhibits weak magnetization (∼0.02μB/Fe) and an antiferromagnetic order. The magnetic hysteresis loops exhibit exchange bias and vertical asymmetry which could be because of spin pinning at the boundaries between ferromagnetic and antiferromagnetic domains. Interestingly, both the calorimetric and dielectric permittivity data in nanoscale BiFeO3 exhibit characteristic features at the magnetic transition point. These features establish the formation of a true ferromagnetic-ferroelectric system with a coupling between the respective order parameters in nanoscale BiFeO3. [ABSTRACT FROM AUTHOR]