1,362 research outputs found
Low temperature study of field induced antiferro-ferromagnetic transition in Pd doped FeRh
The first order antiferromagnetic (AFM) to ferromagnetic (FM) transition in
the functional material Fe49(Rh0.93Pd0.07)51 has been studied at low
temperatures and high magnetic fields. We have addressed the non-monotonic
variation of lower critical field required for FM to AFM transition. It is
shown that critically slow dynamics of the transition dominates below 50 K. At
low temperature and high magnetic field, state of the system depends on the
measurement history resulting in tunable coexistence of AFM and FM phases. By
following cooling and heating in unequal magnetic field (CHUF) protocol it is
shown that equilibrium state at 6 Tesla magnetic field is AFM state. Glass like
FM state at 6 T (obtained after cooling in 8 T) shows reentrant transition with
increasing temperature; viz. devitrification to AFM state followed by melting
to FM state.Comment: 8 pages, 7 figure
Real Space Visualization of Thermomagnetic Irreversibility within Supercooling and Superheating Spinodals in using Scanning Hall Probe Microscopy
Phase coexistence across disorder-broadened and magnetic-field-induced first
order antiferromagnetic to ferrimagnetic transition in polycrystalline
has been studied mesoscopically by Scanning Hall Probe
Microscope at 120K and up to 5 Tesla magnetic fields. We have observed
hysteresis with varying magnetic field and the evolution of coexisting
antiferromagnetic and ferrimagnetic state on mesoscopic length scale. These
studies show that the magnetic state of the system at low field depends on the
path followed to reach 120 K. The low field magnetic states are mesoscopically
different for virgin and second field increasing cycle when 120 K is reached by
warming from 5K, but are the same within measurement accuracy when the
measuring temperature of 120K is reached from 300K by cooling
CONSUMER ACCEPTANCE OF GMO COWPEAS IN SUB-SAHARA AFRICA
Cowpea is the most important indigenous African grain legume for both home use and as a cash crop. Because of its tolerance to drought it is especially important for the Sahel. Genetic transformation of cowpea with Bachilius Thurengius (Bt) genes to control pod boring insects has many advantages, but little is known of the potential consumer response. This paper analyzes and reports the results of a survey of 200 consumers in northern Nigeria in early 2003 concerning consumer awareness of and acceptance of biotechnology. Ninety percent of the respondents were aware of GM products. Those respondents who were most concerned about the ethics of genetic transformation were likely to disapprove of such products, while those individuals who identified international radio as an information source were more likely to approve of GM technology.Institutional and Behavioral Economics,
Modeling of Soil Profile Produced by a Single Sweep Tool
Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 8 (2006): Modeling of Soil Profile Produced by a Single Sweep Tool. Manuscript PM 06 008. Vol. VIII. May, 2006
Measurement of the topological surface state optical conductance in bulk-insulating Sn-doped BiSbTeS single crystals
Topological surface states have been extensively observed via optics in thin
films of topological insulators. However, in typical thick single crystals of
these materials, bulk states are dominant and it is difficult for optics to
verify the existence of topological surface states definitively. In this work,
we studied the charge dynamics of the newly formulated bulk-insulating Sn-doped
BiSbTeS crystal by using time-domain terahertz
spectroscopy. This compound shows much better insulating behavior than any
other bulk-insulating topological insulators reported previously. The
transmission can be enhanced an amount which is 5 of the zero-field
transmission by applying magnetic field to 7 T, an effect which we believe is
due to the suppression of topological surface states. This suppression is
essentially independent of the thicknesses of the samples, showing the
two-dimensional nature of the transport. The suppression of surface states in
field allows us to use the crystal slab itself as a reference sample to extract
the surface conductance, mobility, charge density and scattering rate. Our
measurements set the stage for the investigation of phenomena out of the
semi-classical regime, such as the topological magneto-electric effect.Comment: 5 pages, 3 figures, submitted in Augus
Resonance-state-induced superconductivity at high Indium contents in In-doped SnTe
We report a reinvestigation of superconducting SnInTe at both
low and high In doping levels. Analysis of the superconductivity reveals a
fundamental change as a function of \textit{x}: the system evolves from a
weakly coupled to a strongly coupled superconductor with increasing indium
content. Hall Effect measurements further show that the carrier density does
not vary linearly with Indium content; indeed at high Indium content, the
samples are overall \textit{n}-type, which is contrary to expectations of the
standard picture of In replacing Sn in this material. Density
functional theory calculations probing the electronic state of In in SnTe show
that it does not act as a trivial hole dopant, but instead forms a distinct,
partly filled In 5\textit{s} - Te 5\textit{p} hybridized state centered around
E, very different from what is seen for other nominal hole dopants such as
Na, Ag, and vacant Sn sites. We conclude that superconducting In-doped SnTe
therefore cannot be considered as a simple hole doped semiconductor.Comment: 12 pages and 7 figure
Anomalous conductivity tensor in the Dirac semimetal Na_3Bi
Na3Bi is a Dirac semimetal with protected nodes that may be sensitive to the
breaking of time-reversal invariance in a magnetic field B. We report
experiments which reveal that both the conductivity and resistivity tensors
exhibit robust anomalies in B. The resistivity is B-linear up to 35
T, while the Hall angle exhibits an unusual profile approaching a
step-function. The conductivities and share
identical power-law dependences at large B. We propose that these significant
deviations from conventional transport result from an unusual sensitivity of
the transport lifetime to B. Comparison with Cd3As2 is made.Comment: 8 pages, 5 figure
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