Sungmu Kang

Large low field magnetoresistance in La0.67Sr0.33MnO3 nanowire devices

Large low field magnetoresistance (LFMR) of about 28% is observed in La0.67Sr0.33MnO3 nanowires with 80 nm in diameter at T=300 K. A gradual decrease in the LFMR has been found with increase in wire diameter. The LFMR drops to zero for wires above 280 nm in diameter. The nanowires are grown by means of electrospinning process and exhibit distorted orthorhombic crystal structure. The large LFMR is considered as a grain boundary effect as observed in several perovskite systems. The large LFMR observed in these manganites with reduced dimensions may be useful for room temperature device applications.

Electrical and Magnetic Properties of Higher Manganese Silicide Nanostructures

Higher manganese silicide, Mn15Si26, nanostructures were grown using CVD using a coordination compound precursor. These nanostructures exhibit p-type semiconducting behavior. They also exhibit a nonzero magnetic moment even at room temperature and the magnetic transition temperature appears to be near 330 K.

Synthesis and characterization of FeGa nanowires

We report the growth, structural characterization, and magnetic properties of ferromagnetic Fe0.8Ga0.2 nanowires that are grown on quartz substrates by electrospinning. Electrospun nanowires are annealed in ultrahigh purity argon-hydrogen gas mixture. Uniform, continuous, high aspect ratio FeGa nanowires with diameters in the range of 50–500 nm and lengths of up to 500 μm are grown. Hysteresis loops were measured with magnetic field applied perpendicular and parallel to the substrate plane at 4 and 300 K. The nanowires exhibit a quite large coercivity (380 Oe) at 4 K in the parallel field. At 300 K, they show lower coercivities than that of bulk FeGa in both directions.

Multi-WO3 nanowire based gas detector

The authors have grown high quality WO3 nanowires and fabricated devices with single and multiple nanowires. Devices with single WO3 nanowire exhibit n-type semiconducting behavior and the conductivity increases with hydrogen annealing. The authors also demonstrate significant gas sensitivity of multi-WO3 nanowire devices at room temperature. The sensitivity measurements are carried out in a field-effect transistor geometry with many nanowires connected in between the source and drain electrodes. The sensitivity can be tuned with gate voltages, which will be useful for several applications where controlled gas adsorption is required.