339 research outputs found
South Dakota Corn Performance Test, 1943
The South Dakota Corn Performance Test was designed to supply impartial information concerning hybrids and open-pollinated varieties to the farmers, hybrid-seed-corn dealers and producers, and other persons interested in corn. The plots for this test were in nine areas of eastern South Dakota. There were 362 entries comprising 144 different hybrids and open-pollinated varieties. Two or three adapted open-pollinated varieties were planted in each plot as check varieties. Data are presented on yield, moisture percentage of the grain at harvest, lodging, smut, height, and stand. It should be emphasized that there are many hybrids which have performed well in South Dakota and that the top hybrid in any district for any one year is not necessarily the best one. Statistical measures are included to be used in weighing the advantage or disadvantage of purchasing a given hybrid. Long-time averages are the best indication of the performance of a hybrid. Used with discretion, these data will provide readers with valuable information on the production, sale, and purchase of hybrid corn
The 1942 South Dakota Hybrid Corn Yield Test
Until recently replacement of open-pollinated corn varieties by hybrids has not been as rapid in South Dakota as in states farther east. This reluctance to change has been due primarily to the difficulty of ascertaining the hybrids which will produce the largest average yield under the extremely variable climatic conditions prevalent in the corn growing area of South Dakota. It has been the purpose of these tests to supply information to the purchaser of hybrid corn seed which will enable him to choose adapted high yielding hybrids for his area, and also to provide the producer of hybrid strains with the data necessary to the development of better combinations. As a result of the collection of such data by this and other means the hybrid corn acreage in South Dakota is increasing rapidly
Role of critical spin fluctuations in ultrafast demagnetization of transition-metal rare-earth alloys
Ultrafast magnetization dynamics induced by femtosecond laser pulses have
been measured in ferrimagnetic Co0.8Gd0.2, Co.74Tb.26 and Co.86Tb.14 alloys.
Using element sensitivity of X-ray magnetic circular dichroism at the Co L3, Tb
M5 and Gd M5 edges we evidence that the demagnetization dynamics is element
dependent. We show that a thermalization time as fast as 280 fs is observed for
the rare-earth in the alloy, when the laser excited state temperature is below
the compensation temperature. It is limited to 500 fs when the laser excited
state temperature is below the Curie temperature (Tc). We propose critical spin
fluctuations in the vicinity of TC as the mechanism which reduces the
demagnetization rates of the 4f electrons in transition-metal rare-earth alloys
whereas at any different temperature the limited demagnetization rates could be
avoided.Comment: 11 pages, 4 figure
Non-universality of artificial frustrated spin systems
Magnetic frustration effects in artificial kagome arrays of nanomagnets with
out-of-plane magnetization are investigated using Magnetic Force Microscopy and
Monte Carlo simulations. Experimental and theoretical results are compared to
those found for the artificial kagome spin ice, in which the nanomagnets have
in-plane magnetization. In contrast with what has been recently reported, we
demonstrate that long range (i.e. beyond nearest-neighbors) dipolar
interactions between the nanomagnets cannot be neglected when describing the
magnetic configurations observed after demagnetizing the arrays using a field
protocol. As a consequence, there are clear limits to any universality in the
behavior of these two artificial frustrated spin systems. We provide arguments
to explain why these two systems show striking similarities at first sight in
the development of pairwise spin correlations.Comment: 7 pages, 6 figure
Ultrasensitive 3He magnetometer for measurements of high magnetic fields
We describe a 3He magnetometer capable to measure high magnetic fields (B >
0.1 Tesla) with a relative accuracy of better than 10^-12. Our approach is
based on the measurement of the free induction decay of gaseous, nuclear spin
polarized 3He following a resonant radio frequency pulse excitation. The
measurement sensitivity can be attributed to the long coherent spin precession
time T2* being of order minutes which is achieved for spherical sample cells in
the regime of motional narrowing where the disturbing influence of field
inhomogeneities is strongly suppressed. The 3He gas is spin polarized in-situ
using a new, non-standard variant of the metastability exchange optical
pumping. We show that miniaturization helps to increase T2* further and that
the measurement sensitivity is not significantly affected by temporal field
fluctuations of order 10^-4.Comment: 27 pages, 7 figure
Electric-power efficiency of anomalous Hall current
The electric-power dissipation of the anomalous-Hall current injected into a
lateral load circuit is studied. The anomalous-Hall current is generated by a
ferrimagnetic Hall bar and injected into lateral
contacts lithographied at the two edges. The current, the voltage and the power
injected in the lateral circuit are studied as a function of the magnetization
state, the load resistance , and the temperature. The power efficiency
shows a sharp maximum as a function , which corresponds to the condition
of the resistance matching of the two sub-circuits. The maximum power
efficiency is of the order of the square of anomalous-Hall angle. The
observations are in agreement with recent predictions based on a
non-equilibrium variational approach.Comment: 12 pages, 4 Figure
Light-induced magnetization reversal of high-anisotropy TbCo alloy films
Magnetization reversal using circularly polarized light provides a new way to
control magnetization without any external magnetic field and has the potential
to revolutionize magnetic data storage. However, in order to reach ultra-high
density data storage, high anisotropy media providing thermal stability are
needed. Here, we evidence all-optical magnetization switching for different
TbxCo1-x ferrimagnetic alloy composition and demonstrate all-optical switching
for films with anisotropy fields reaching 6 T corresponding to anisotropy
constants of 3x106 ergs/cm3. Optical magnetization switching is observed only
for alloys which compensation temperature can be reached through sample
heating
Phase transition in ultrathin magnetic films with long-range interactions: Monte Carlo simulation of the anisotropic Heisenberg model
Ultrathin magnetic films can be modeled as an anisotropic Heisenberg model
with long-range dipolar interactions. It is believed that the phase diagram
presents three phases: An ordered ferromagnetic phase I, a phase characterized
by a change from out-of-plane to in-plane in the magnetization II, and a
high-temperature paramagnetic phase III. It is claimed that the border lines
from phase I to III and II to III are of second order and from I to II is first
order. In the present work we have performed a very careful Monte Carlo
simulation of the model. Our results strongly support that the line separating
phases II and III is of the BKT type.Comment: 7 page
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