Magnetic hysteresis

About: Magnetic hysteresis is a research topic. Over the lifetime, 12665 publications have been published within this topic receiving 253100 citations.

Driving apparatus of proportional magnetic valve

Abstract: PURPOSE:To eliminate the effect of the magnetic hysteresis onto the attraction force of a magnetic proportional valve due to material by driving the magnetic valve through controlling the ON-time in the same frequency of the pulse wave, in the proportional control valve which proportionally controls the flow rate of the fluid in a gas combustor. CONSTITUTION:The temperature of the flow rate which is detected in the detection part A is compared with the set value in the comparison part B, and the pulse signal having the width proportional to the magnitude of the flow rate which is determined by the difference described above is fed into a magnetic valve D from the pulse generating part E. The frequencies of the pulse waves for the flow rates l, (m), and (n) are equal, and the ON- time is different according to the magnitude of the flow rate. When a pulse wave is fed into a coil 1, the attractive force proportional to the average electric power is generated, and a movable core 2 stops at the position in balance with a spring 4, and the distance between a valve piece 3 and a valve seat 6 is adjusted, and the flow rate is controlled. Therefore, the effect of the magnetic hysteresis onto the attractive force of the proportional magnetic valve due to material can be eliminated.

Exchange Bias Effect Concerned with Tunneling Magnetoresistance in ${\hbox{Sm}}_{0.35} {\hbox{Pr}}_{0.15}{\hbox{Sr}}_{0.5}{\hbox{MnO}}_3$ Phase Separated Manganites

Abstract: In this paper, we report the exchange bias (EB) effect along with tunneling magnetoresistance (MR) in polycrystalline Sm0.35Pr0.15Sr0.5MnO3 manganite. Analogous to the shift in the magnetic hysteresis loop along the field (H)-axis, a shift is also observed in the MR-H curve when the sample is cooled in a static dc magnetic field at 5 K. The values of exchange fields (HE), coercivity (HC), remanence asymmetry (ME) and magnetic coercivity (MC) are found to strongly depend on cooling magnetic field and temperature. Magnetic training effect (TE) is supportive experimental evidence which describes the decrease of exchange bias field when sample is successively field-cycled at a particular temperature. We have also observed TE in the shift of the MR-H curve which has been interpreted by the spin relaxation model. We have observed the time dependent resistivity below the spin freezing temperature. The unusual MR behavior is interpreted in terms of the intragranular interface effect between short-range ferromagnetic clusters and spin-glass matrix giving rise to the EB effect, which is of special interest for potential application in multifunctional spintronic devices.

Magnetization of Co elements sensed by semiconductor transport magnetometry and transmission electron microscopy

Abstract: Magnetization reversal in 300 nm Co squares has been investigated by semiconductor transport magnetometry using a Hall bar containing a two-dimensional electron gas. In this technique the local field from a regular array of magnetic elements patterned on top of the Hall bar changes the measured longitudinal magnetoresistance, enabling the magnetization of the elements to be deduced. Hysteresis loops obtained from the magnetoresistance curve showed a zero magnetization state at zero applied field, which was confirmed by transmission electron microscopy imaging and micromagnetic modelling to represent a vortex state. Repeatable fields were found for vortex expulsion and re-entry, with strong dependence on element size but rather weak dependence on film thickness.