摘要:

Transfer impedance of a variety of soft magnetic materials (Ni, Fe, Ni&sngbnd;Fe and Fe&sngbnd;Si alloys) has been measured for the frequency range 0.01 to greater than 100 kHz. At frequencies above about 10 kHz, it is shown that ferromagnetic materials can have lower transfer impedance than copper. In magnetic materials, the occurrence of low impedance appears to be related to magnetic softness, whether attained through choice of composition or through annealing treatments.

ISSN:0021-8979    

DOI:10.1063/1.1660437

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A new permeameter measures the magnetizing force and the corresponding magnetic induction up to the temperature of 1000°C in a vacuum or an inert atmosphere. Two massive symmetrical yokes close the magnetic path around the specimen which consists of a rod of solid material or a bundle of sheet material. The yokes are made of a specially processed alloy of 9% iron, 91% cobalt, a high‐temperature soft magnetic material. A coil surrounding the specimen supplies a magnetizing force of up to 100 Oe and a separate coil is used to measure the magnetic induction. Auxiliary coils provide additional magnetizing force resulting in a longitudinal distribution of flux uniform to within 1%. The magnetizing force is calculated from the coil current while a fluxmeter is used for the induction. The null‐balance‐type permeameter utilizes the magnetic potentiometer principle with yoke compensating coils to cancel the effects of the reluctance of the yoke and the joint gaps. Very close agreement was obtained at room temperature when compared to the standards laboratory MH and Fahy type permeameters. Normal induction curves as a function of temperature for the yoke material are also presented.

ISSN:0021-8979    

DOI:10.1063/1.1660438

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

As compared to AISI Grade M‐15 electrical steel, the use of cube textured 3% Si&sngbnd;Fe steel, 0.012‐in. thick, as limination material in cores of 400‐Hz generators covering ratings between 15 and 90 kVA, brought about improvements in generator weight, stack length, efficiency, and voltage transients. Conventional core fastening and stress‐relief annealing practices were applicable, but stress concentrations during lamination punching had to be minimized in order to prevent cleavage cracks in the highly cube‐textured material.

ISSN:0021-8979    

DOI:10.1063/1.1660439

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Magnetic flux in ``E'' and ``L'' stampings made from cube‐on‐edge‐oriented 3.25% Si&sngbnd;Fe must pass through the hardest magnetic direction at the corners of the ``E'' and ``L.'' This work shows how electron beam welding and grain growth can be used to form closed, flat, core specimens, in which the flux path is parallel with the easy direction of magnetization in all parts of the specimens. The magnetic properties of these cores are comparable with magnetic properties of Epstein specimens of the same material, having an induction of 19 800 G at 50 Oe magnetizing force, coercive force of 0.094 Oe, and maximum permeability of 53 000.

ISSN:0021-8979    

DOI:10.1063/1.1660440

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Magnetic domains have been observed in rf‐dc sputtered films of TbFeO3epitaxially grown on (001) YAlO3and (011¯2) sapphire. The size of the domains in the demagnetized state increased with increasing film thickness, while the complexity of their form decreased. The coercivity of the films on YAlO3was lower than of those on sapphire, with the lowest value of 10 Oe observed over very small areas.

ISSN:0021-8979    

DOI:10.1063/1.1660441

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The spin reorientation phenomenon in materials such as the orthoferrites can be used for thermomagnetic writing. This mechanism has been used to write into platelets of Sm0.7Er0.3FeO3which has its spin reorientation just above room temperature. Curie point writing can be done in those orthoferrites in which there is no spin reorientation in the working temperature range. Spots 5 &mgr; in diameter were written into 2‐&mgr;‐thick sputtered epitaxial TbFeO3films by the Curie technique to demonstrate the feasibility of high storage densities.

ISSN:0021-8979    

DOI:10.1063/1.1660442

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The effect of lattice and thermal mismatch on the coercive force and the perfection of GdIG films grown by chemical vapor deposition has been studied. The films were deposited on YAG, GdGaG, and mixed (GdNd) GaG and (GdLa) GaG substrates, which were prepared with lattice parameters closely matching the lattice parameter of GdIG. A decrease in coercive force by a factor of four was found between films grown on YAG and Gd0.75Nd2.25GaG substrates. This improvement is discussed in terms of interfacial and volume strains which are caused by lattice and thermal mismatch.

ISSN:0021-8979    

DOI:10.1063/1.1660443

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Flux reversal in epitaxial Ni&sngbnd;Fe thin films has been studied with use of a 10‐nsec exposure time Kerr magneto‐optic camera. The epitaxial films exhibit biaxial anisotropy and both 90° and 180° switching may occur. When the switching field is applied antiparallel to the saturated magnetization, the switching processes are similar to the corresponding processes in polycrystalline films. When the field is applied at an obtuse angle to the saturated magnetization, stripe‐like domains form that lie along the hard axis (45° to easy axes). With very low‐drive fields the boundaries between stripes are 90° walls, but with higher fields the wall angle is much smaller, and the stripes appear like a large amplitude, large wavelength ripple. If the field is applied at an angle greater than 135° to the saturated magnetization, 180° domains nucleate and complete the switching after the stripes form. With angles less than 135°, the switching is completed by the formation of additional stripes and the rotation of the magnetization in nonswitched stripes.

ISSN:0021-8979    

DOI:10.1063/1.1660444

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Stripe domains were observed in sputtered Co&sngbnd;Al films 350–700‐Å thick. This type of domain structure has been reported previously only in much thicker ferromagnetic films. The structure of the films determined by electron diffraction showed the stripe domains were associated with a bcc structure similar to iron. Saturation magnetization was measured with a vibrating sample magnetometer and was found to vary linearly with film composition, but had no relationship to the formation of stripes. The domains were observed by Lorentz microscopy and could be removed by a saturating field, but reappeared, contrary to the case reported on Ni&sngbnd;Fe films when an ac field was applied.

ISSN:0021-8979    

DOI:10.1063/1.1660445

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Magnetic domain propagation behavior in narrow channels composed of a Permalloy thin film imbedded in a high coercive film is discussed in this paper. The domain propagation is affected by channel shape and by magnetic potential barriers in the channel. The domain‐wall velocity along the channel can be controlled by the demagnetizing field in the channel. The domain grows along the channel under applied pulse fields. To obtain a stepwise movement of domain wall under pulse fields, periodic barriers of magnetic potential comprising high coercive force film were introduced. When the demagnetizing field in the channel is larger than 1/3 of the intrinsic coercive force of the channel material, an oval domain nucleates and shifts along the channel under successive applied field pulses. Reversed domains are observed using the Kerr magneto‐optic effect.

ISSN:0021-8979    

DOI:10.1063/1.1660446

出版商:AIP    

年代:1971

数据来源: AIP