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Bourne, H. C., Jr.

Publications and source records attributed to Bourne, H. C., Jr..

18 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Effects of dc bias on the fabrication of amorphous GdCo RF sputtered films

An investigation has been conducted on the effects of a dc bias field applied to Gd(1-x)Co(x) thin films during RF sputter deposition. Such films may possess uniaxial magnetic anisotropy with easy axis perpendicular to the plane of the film and may be used in magnetic bubble devices. Uniformity in composition, thickness and magnetic properties has been achieved and film composition has been controlled to within one percent. However, significant variations of magnetic properties were observed from film to film.

Bourne, H. C., Jr.↗
NASA NTRS1974

Transient and steady-state velocity of domain walls for a complete range of drive fields

Approximate analytic solutions for transient and steady-state 180 deg domain-wall motion in bulk magnetic material are obtained from the dynamic torque equations with a Gilbert damping term. The results for the Walker region in which the transient solution approaches the familiar Walker steady-state solution are presented in a slightly new form for completeness. An analytic solution corresponding to larger drive fields predicts an oscillatory motion with an average value of the velocity which decreases with drive field for reasonable values of the damping parameter. These results agree with those obtained by others from a computer solution of the torque equation and those obtained by others with the assumption of a very large anisotropy field.

Bourne, H. C., Jr.↗
NASA NTRS1974

Transient and steady-state velocity of domain walls for a complete range of drive fields

Approximate analytic solutions for transient and steady-state 180 deg domain wall motion in bulk magnetic material are obtained from the dynamic torque equations with a Gilbert damping term. The results for the Walker region in which the transient solution approaches the familiar Walker steady-state solution are presented in a slightly new form for completeness. An analytic solution corresponding to larger drive fields predicts an oscillatory motion with an average value which decreases with drive field for reasonable values of the damping parameter. These results agree with those obtained by a computer solution of the torque equation and those obtained with the assumption of a very large anisotropy field.

Bourne, H. C., Jr.↗
NASA NTRS1972

Wall contraction in Bloch wall films.

The phenomenon of wall contraction characterized by a peak in the velocity-field relationship and a region of negative differential mobility is observed in uniaxial magnetic thin films of various magnetic properties by careful interrupted-pulse experiments. The observed results agree quite well with the theory for bulk samples when the extensive flux closure of thin film walls is accounted for by a suitable empirical scaling factor.

Bartran, D. S.↗
NASA NTRS1972

Low-frequency creep in CoNiFe films.

Domain wall motion excited by slow rise-time, bipolar, hard-axis pulses in vacuum deposited CoNiFe films from 1500 to 2000 A thick is studied. The results are consistent with those of comparable NiFe films. Furthermore, the wall coercivity is found to be the most significant sample property correlated to the low-frequency creep properties of all the samples.

Bartran, D. S.↗
NASA NTRS1972

Wall contraction in Bloch wall films

The phenomenon of wall contraction characterized by a peak in the velocity field relationship and a region of negative differential mobility is observed. Uniaxial magnetic thin films of various compositions and magnetic properties are studied in careful interrupted pulse experiments. The observed results agree quite well with the theory for bulk samples.

Bartran, D. S.↗
NASA NTRS1972

Low frequency creep in CoNiFe films

The results of an investigation of domain wall motion excited by slow rise-time, bipolar, hard-axis pulses in vacuum deposited CoNiFe films 1500A to 2000A thick are presented. The results are consistent with those of comparable NiFe films in spite of large differences in film properties. The present low frequency creep data together with previously published results in this and other laboratories can be accounted for by a model which requires that the wall structure change usually associated with low frequency creep be predominately a gyromagnetic process. The correctness of this model is reinforced by the observation that the wall coercive force, the planar wall mobility, and the occurrence of an abrupt wall structure change are the only properties closely correlated to the creep displacement characteristics of a planar wall in low dispersion films.

Bartran, D. S.↗
NASA NTRS1972

A transient solution for domain wall motion

An analytic solution of transient wall motion in a bulk ferromagnetic material is obtained from the dynamic torque equations with a Gilbert damping term. The steady state solution reduces to previously obtained, well known solutions.

Bourne, H. C., Jr.↗