31 research outputs found
Some factors that may influence the invasiveness of Mikania micrantha Kunth. ex. H.B.K. in Fiji
Frequency and density of Mikania micrantha and other weeds in taro and banana systems in eastern Viti Levu, Fiji
Niobium shielded sapphire resonator for field-dependent surface resistance measurements of superconducting films
Electrically-driven phase transition in magnetite nanostructures
Magnetite (FeO), an archetypal transition metal oxide, has been
used for thousands of years, from lodestones in primitive compasses[1] to a
candidate material for magnetoelectronic devices.[2] In 1939 Verwey[3] found
that bulk magnetite undergoes a transition at T 120 K from a
high temperature "bad metal" conducting phase to a low-temperature insulating
phase. He suggested[4] that high temperature conduction is via the fluctuating
and correlated valences of the octahedral iron atoms, and that the transition
is the onset of charge ordering upon cooling. The Verwey transition mechanism
and the question of charge ordering remain highly controversial.[5-11] Here we
show that magnetite nanocrystals and single-crystal thin films exhibit an
electrically driven phase transition below the Verwey temperature. The
signature of this transition is the onset of sharp conductance switching in
high electric fields, hysteretic in voltage. We demonstrate that this
transition is not due to local heating, but instead is due to the breakdown of
the correlated insulating state when driven out of equilibrium by electrical
bias. We anticipate that further studies of this newly observed transition and
its low-temperature conducting phase will shed light on how charge ordering and
vibrational degrees of freedom determine the ground state of this important
compound.Comment: 17 pages, 4 figure
Log export restrictions and trade policies in the Philippines: bane or blessing to sustainable forest management?
Vegetative production and development of Mikania micrantha in taro and cassava production in Viti Levu, Fiji
The impact of rainfall upon pollination and reproduction of Mikania micrantha in Viti Levu, Fiji
A compensating monochromator crystal bender at the HMI multipole wiggler beamline MAGS
A compensating watercooled crystal bender for high heat loads has been built and successfully commissioned at the new multipole wiggler beamline MAGS of the Hahn Meitner Institute at the synchrotron radiation source BESSY. The beamline takes a 3 x 0.3 mrad fan of the wiggler beam, corresponding to a heat load of up to 2000 W. Although the crystal bender was originally designed for maximum heat loads of 600 W, it was found to work with heat loads of up to 800 W, reducing the Si 111 rocking curve width from 22 to 11 arcsec at the Cu K edge 8.9 keV . In addition, the good mechanical reproducibility of the device is illustrate