Magnetic domain wall propagation in a submicron spin-valve stripe: influence of the pinned layer

The propagation of a domain wall in a submicron ferromagnetic spin-valve stripe is investigated using giant magnetoresistance. A notch in the stripe efficiently traps an injected wall stopping the domain propagation. The authors show that the magnetic field at which the wall is depinned displays a stochastic nature. Moreover, the depinning statistics are significantly different for head to head and tail-to-tail domain walls. This is attributed to the dipolar field generated in the vicinity of the notch by the pinned layer of the spin-valve

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

Chiral nature of magnetic monopoles in artificial spin ice

Micromagnetic properties of monopoles in artificial kagome spin ice systems are investigated using numerical simulations. We show that micromagnetics brings additional complexity into the physics of these monopoles that is, by essence, absent in spin models: besides a fractionalized classical magnetic charge, monopoles in the artificial kagome ice are chiral at remanence. Our simulations predict that the chirality of these monopoles can be controlled without altering their charge state. This chirality breaks the vertex symmetry and triggers a directional motion of the monopole under an applied magnetic field. Our results also show that the choice of the geometrical features of the lattice can be used to turn on and off this chirality, thus allowing the investigation of chiral and achiral monopoles.Comment: 10 pages, 4 figure

Wide range and tunable linear TMR sensor using two exchange pinned electrodes

A magnetic tunnel junction sensor is proposed, with both the detection and the reference layers pinned by IrMn. Using the differences in the blocking temperatures of the IrMn films with different thicknesses, crossed anisotropies can be induced between the detection and the reference electrodes. The pinning of the sensing electrode ensures a linear and reversible output. It also allows tuning both the sensitivity and the linear range of the sensor. The authors show that the sensitivity varies linearly with the ferromagnetic thickness of the detection electrode. It is demonstrated that an increased thickness leads to a rise of sensitivity and a reduction of the operating range

Quick X-ray microtomography using a laser-driven betatron source

Laser-driven X-ray sources are an emerging alternative to conventional X-ray tubes and synchrotron sources. We present results on microtomographic X-ray imaging of a cancellous human bone sample using synchrotron-like betatron radiation. The source is driven by a 100-TW-class titanium-sapphire laser system and delivers over $10^8$ X-ray photons per second. Compared to earlier studies, the acquisition time for an entire tomographic dataset has been reduced by more than an order of magnitude. Additionally, the reconstruction quality benefits from the use of statistical iterative reconstruction techniques. Depending on the desired resolution, tomographies are thereby acquired within minutes, which is an important milestone towards real-life applications of laser-plasma X-ray sources

360 degree domain wall generation in the soft layer of magnetic tunnel junctions

High spatial resolution X-ray photo-emission electron microscopy technique has been used to study the influence of the dipolar coupling taking place between the NiFe and the Co ferromagnetic electrodes of micron sized, elliptical shaped magnetic tunnel junctions. The chemical selectivity of this technique allows to observe independently the magnetic domain structure in each ferromagnetic electrode. The combination of this powerful imaging technique with micromagnetic simulations allows to evidence that a 360 degree domain wall can be stabilized in the NiFe soft layer. In this letter, we discuss the origin and the formation conditions of those 360 degree domain walls evidenced experimentally and numerically