摘要:

An investigation was made to examine the influence of V levels up to 0.10 w/o on the magnetic properties of Al‐killed low carbon steels having 0.052/0.054 initial C, 0.36/0.37 Mn, 0.11/0.12 P, 0.022/0.024 S and 0.028/0.031 w/o Al. The processing sequence for these steels involved hot rolling, pickling, hot band annealing, cold rolling and high temperature annealing following decarburization. The results showed that the longitudinal permeability at 17 and 18 kG increases sharply with the addition of V up to 0.10 w/o. In contrast to improved permeability, the 15 kG core loss is essentially unaffected by changes in V concentration. According to the classical model, the computed anomalous loss in these steels constitutes approximately 25&percent; of the total loss, which is a characteristic of the grain‐oriented steel. Improvements in high induction permeabilities are directly related to the increase in B10(induction at 10 Oe) which describes the sharpness of the Goss‐texture. This relationship implies that the presence of V is required to develop a sharper Goss‐texture in the steel. Electronmicroscopy results suggest that this texture is formed as a result of the precipitation of fine VN particles.

ISSN:0021-8979    

DOI:10.1063/1.327009

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Saturation magnetostriction was measured in polycrystalline excess‐iron NiZnCo ferrite over a broad range in compositions. The stoichiometric compositions were Ni2+1−x−y−zZn2+xCo2+yFe2+zFe3+2O4where 0<x<0.63, 0<y<0.019, 0.11<z<0.57. By oxidizing the samples, the Fe2+content was varied for a given molar composition from nearly the maximum allowable (stoichiometric) to 1&percent; of this maximum (oxidized). This study presents the first magnetostriction measurements on oxidized ferrite, which is used extensively in devices due to its low magnetic loss. A single ion model of the magnetostrictive contributions of Fe2+, Fe3+, Ni2+, and Co2+ions is formulated and compared to the data.

ISSN:0021-8979    

DOI:10.1063/1.327010

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The magnetization in Li0.5−z/2ZnzFe2.5−z/2O4with z=0.0, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 has been measured at 30 K and at applied magnetic fields of up to 100 kOe. The magnetization for samples with z?0.2 saturated at less than 10 kOe. The magnetization for samples with z?0.3 did not saturate. Rather, for applied fields in excess of 30 kOe, these samples exhibited field‐independent differential susceptibilities ranging from 1.68×10−5emu/g‐Oe for z=0.3 to 20.66×10−5emu/g‐Oe for z=0.7. The high‐field susceptibilities are attributed to localized canting of octahedral site Fe3+spins with fewer than three tetrahedral site Fe3+nearest neighbors. Susceptibilities predicted by existing localized canting models are in qualitative agreement with the data, but predicted values for large z are too small.

ISSN:0021-8979    

DOI:10.1063/1.327011

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The coercivity of NiFe (80/20) films can be lowered by laminating several layers with nonmagnetic spacers. A reduction by a factor of 10 can be achieved with a simple bi‐layer, regardless of spacer material, provided the spacer thickness is below a critical value. No further reduction is found for multilayers. Two peaks of Hcnear thicknesses of 250A˚ and 1000A˚ for single layer films, associated with changes in domain structure, are suppressed by lamination. After a minimum spacer thickness (S) of 10–15A˚, the domain walls in the separate layers no longer coincide but track closely, their separation depending on S. With S?100A˚ the layers switch independently, giving rise to multiple values of Hc.

ISSN:0021-8979    

DOI:10.1063/1.326960

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The response of an ideally soft magnetic cylinder is calculated by approximating magnetostatic interactions while taking into account the exchange energy of curling patterns with point singularities. Detailed calculations of the magnetic surface charge distribution of paramagnetic materials are used as a guide in parameterizing an approximate charge distribution suitable for applying the Ritz method to the micromagnetic problem of ferromagnetic materials without anisotropy or magnetostriction. Numerical results are given for a cylinder with L/D=1 for fields below saturation illustrating how remanence and coercivity depend on the ratio of the exchange length A/M2oto sample dimensions. The role of point singularities in remanence, coercivity, nucleation and irreversibility is outlined.

ISSN:0021-8979    

DOI:10.1063/1.326961

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

When a magnetized tape in an oppositely directed field is rubbed, the stress &sgr; reduces the switching field by an amount &Dgr;H&sgr;so as to produce a partial reversal of the magnetization &Dgr;MH,&sgr;. This inverse magnetostrictive effect leads to the playback loss &Dgr;L that is observed in a recorded tape. The loss depends on &Dgr;H&sgr;, the coercive force Hc, the demagnetizing field and the shape of the hysteresis loop. The parameter &Dgr;H&sgr;is proportional to &sgr; and is related to the magnetostriction constants. It can exceed 300 Oe or greater than one half the coercive force in a 3.5&percent; Co‐doped &ggr;‐Fe2O3sample when &sgr;=500 kg/cm2. When Co is adsorbed on the surface of &ggr;‐Fe2O3particles the saturation magnetostriction ‖&ggr;s‖, &Dgr;H&sgr;and &Dgr;L are all smaller than for a Co‐doped tape with an equivalent Hc. The small &Dgr;L for CrO2is due to its low &lgr;swhereas low stress related losses in Fe are due primarily to a high Hc.

ISSN:0021-8979    

DOI:10.1063/1.326962

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We describe a fully two dimensional self‐consistent calculation of an isolated transition in a thick particulate magnetic recording tape. The calculation includes relative motion between the tape and head, as well as a vector magnetic hysteresis model.

ISSN:0021-8979    

DOI:10.1063/1.326963

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

In order to predict the future trend of the magnetic disc media, we tried to increase the orientation ratio of magnetic particles on &ggr;‐Fe2O3coated discs. By refining the technique of paint‐making, we have realized super‐aligned discs having longitudinal squareness, Mr/Mmof 0.92 and halfwidth of differential M‐H curve, &Dgr;H of 95 Oe with unexpectedly smooth surface. The recording characteristics of the superaligned discs and variously oriented discs were measured using a Mn‐Zn ferrite head. It is found that the reproduced output of highly‐oriented discs is larger than is expected from the increase in Mrand that the half pulsewidth decreases with an increase in Mr/Mm. This suggests the orientation also causes a reduction of magnetization transition length, a. Taking the effect of squareness into consideration, a simple empirical relation, a=&Dgr;H/Hc⋅2tMr/Hc, was introduced and the obtained data were well explained with this relation. From these results and low noise characteristics of oriented discs, we conclude that the highly‐oriented &ggr;‐FeO3coated discs will be suitable for higher recording density, up to 15,000 BPI and 1,000 TPI, having a sufficient S/N ratio.

ISSN:0021-8979    

DOI:10.1063/1.326964

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Recent developments in disc recording have made use of low flying ferrite heads which make sliding contact with the discs during starts and stops. The disc media, comprised of finely dispersed &ggr;‐Fe2O3in a polymer matrix, generates abrasive wear at the head and disc interface. Physical measurements concerning the nature of the wear mechanism and magnetic recording anomalies are reported. Both the head and disc wear were studied respectively and related to flight mechanics, the air bearing, component geometry and structures. The role of boundary lubricants has been investigated and their effect on magnetic and physical performance criteria are discussed.

ISSN:0021-8979    

DOI:10.1063/1.326965

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Ferromagnetic resonance (FMR) spectra were obtained at 9 and 35 GHz for particles of metallic iron precipitated in fused silica containing 1–120 ppm Fe. Accurate g values and anisotropy constants K1, K2and K3were extracted by computer simulation of the powder pattern line shapes, assuming negligible shape anisotropy. One sample, melted under a He‐H2O atmosphere, exhibited anisotropy constants identical with published values for pure &agr;–iron and a g value of 2.081±0.002. Samples strongly reduced in H2displayed smaller values of K1, consistent with expectation for alloying of the Fe with up to 20&percent; Si. These K1values were shown to be statistically distributed and linearly correlated with the g values in the range 5?at.&percent;Si?20. All samples displayed increases ∼ 5–10&percent; in apparent K1value with increasing frequency, either as‐delivered or after aging. It is hypothesized that the latter effects are due to the formation of a magnetic iron oxide layer at the metal‐glass interface.

ISSN:0021-8979    

DOI:10.1063/1.326966

出版商:AIP    

年代:1979

数据来源: AIP