Remanent Magnetization State Research Articles

Resistance of the remanent magnetization state of steel subjected to various heat treatments to the effect of constant demagnetizing fields: 37154 Gorkunov, E.S.; Somova, V.M.; Buldakova, N.B. Soviet Journal of Nondestructive Testing, Vol. 22, No. 9, pp. 586–594 (May 1987)

Resistance of the remanent magnetization state of steel subjected to various heat treatments to the effect of constant demagnetizing fields: 37154 Gorkunov, E.S.; Somova, V.M.; Buldakova, N.B. Soviet Journal of Nondestructive Testing, Vol. 22, No. 9, pp. 586–594 (May 1987)

Epitaxial Fe films on GaAs for hybrid semiconductor-magnetic memories

The magnetic and structural properties of Fe films deposited by ion-beam sputtering (IBS) on (100)-oriented GaAs substrates are described. The films are between 30 and 600 nm thick and are characterized by a coercive field of approximately 3–6 Oe. The saturation magnetization and anisotropy field, inferred from vibrating sample magnetometer measurements agree substantially with the values expected for bulk Fe. Films deposited on the (100) substrate show the expected fourfold (or ‘‘biaxial’’) symmetry with no indication of a uniaxial anisotropy component. These properties make the films ideally suitable for the intended application in a hybrid semiconductor-magnetic memory, in which two magnetic remanent states with mutually orthogonal magnetization directions interact with an electronic flip-flop circuit.

Susceptibility, hysteresis and magnetization states in the CuMn spin glass

AC susceptibilities have been measured at T ⪡ T f on a quenched Cu-8.25 at% Mn sample along the hysteresis curve and especially in remanent magnetization states. Along the M( H)-curve ϰ∥ starts to decrease already below the S-point field H w, when d M/d M is still increasing. After reduction of the external field from H ⪢ H w to zero ϰ ⊥ by far exceeds ϰ ∥, which itself is a little increased above its starting (ZFC) value. Reversing the external field ϰ ∥ develops distinct maxima at the step fields H st. A model is developed considering the spin glass at M r to consist of magnetic moments bound by different anisotropies to preferential directions which are oriented partly at random (anisotropy field H ∗ w), partly along M r (anisotropy field H H ∗ st ⪡ H ∗ w). The model connects both susceptibilities with characteristic parameters of the hysteresis and quantitatively explains the data.

Quiescent core-transistor counters

The paper describes a number of binary counting circuits having junction transistors and square-hysteresis-loop magnetic cores as the basic circuit elements. The cores have two well-defined remanent magnetic states which provide the necessary information storage when the circuit is quiescent, and the transistors are used as pulse-shaping amplifiers which provide output signals and `switch? the cores from one remanent state to the other. Cores of ferrite material made for matrix storage systems are used; they have a change-over time of less than a microsecond and, in conjunction with junction transistors at present available, limit the highest counting rate to 2 × 105 pulses/sec. In the circuits described, the emitter and base contacts of the transistor are connected across a winding on the core. The emitter is earthed, and the collector, via the load, is connected to a source of negative voltage. Other windings are available on the core, and flux change in a specified direction causes the transistor to be turned on. When the flux change is complete, the collector current ceases after a short delay. The pulse duration may be controlled by a bias voltage applied between the emitter and the base. Most of the counting circuits include a regenerative loop back to the core in series with the collector load. Core-transistor circuits consume little mean power and this, coupled with compactness, simplicity and reliability, seems to make the combination very suitable for digital-computer applications.