Engineering topics

Slusky, S. E. G.

Publications and source records attributed to Slusky, S. E. G..

5 records

NASA NTRS1987

Rare-earth substitution in (BiYCa)3(FeSiGe)5O12 bubble films

The substitution of Y by Sm, Tb, Gd, and Ho in (BiYCa)3 FeSiGe)5O12 bubble garnet is shown to have large effects on the growth-induced anisotropy (GIA). The presently accepted film composition intended for 6-or 8-micron-period bubble memory devices demands partial substitution of Y by Gd and Ho. However, comparing films grown under the same growth conditions, it is observed that YGdHoBilG films posess less (GIA) than their Gd, Ho-free counterparts. Thus, to satisfy (GIA) requirements, the supercooling during growth must be increased by 20 K to 80 K with undesirable effects on defect densities. A new film composition containing Sm, Tb, and Gd has been formulated to satisfy all known material property specifications for 6- or 8-micron-period memory devices. It can be grown with only 45-50 K supercooling.

Luther, L. C.↗

NASA NTRS1986

Growth-induced anisotropy in bismuth - Rare-earth iron garnets

The bismuth-doped rare-earth iron garnets, (R3-x-yBixPby)Fe5O12 (Bi:RIG, R = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), were prepared under constant growth conditions to investigate the influence of ionic species on the bismuth-based growth-induced uniaxial anisotropy K(u) exp g. The effect of ionic species on growth-induced anisotropy in Bi:RIG was not consistent with the ionic size model of site ordering. In particular, Bi:SmIG, Bi:EuIG, and Bi:TbIG displayed high growth-induced anisotropies, up to 331,000 erg/cu cm at room temperature for x of about 0.5. The temperature dependence of these K(u) exp gs was somewhat higher than that of the well studied Bi:YIG. The site ordering of Bi can be modeled by assuming that small, low-oxygen-coordination BiOw exp +3-2 w melt complexes have a strong site selectivity for small, high-oxygen coordination sites at the growth interface.

Fratello, V. J.↗

NASA NTRS1986

Effect of diamagnetic substitution on growth-induced anisotropy in (YBi)3Fe5O12

Films of (Y/3-x-y/Bi/x/Pb/y/)(Fe/5-z/Ga/z/)O12(Z = 0-1.1) and (Y/3-x-y/Bi/x/PB/y/)(Fe/5-w/In/w/)O12(w = 0-O.6) garnets were prepared by liquid-phase epitaxy. The effects of tetrahedral Ga and octahedral In substitution on the Bi-based growth-induced uniaxial anisotropy in (Ybi)3Fe5O12 films were measured. Both Ga and In resulted in a linear decrease in the anisotropy with increasing substitution. The effect of octahedral In was twice that of tetrahedral Ga.

Fratello, V. J.↗

NASA NTRS1986

Four-micron period ion-implanted bubble test circuits

Packaged magnetic bubble test circuits made with 4-micron period ion-implanted circuits were operated over -55 to +110 C. The circuits used bidirectional transfer and nondestructive detection and were made on bismuth-containing magnetic garnet films. Passivated circuits that incorporated an improved transfer conductor design were operated on films with higher Gilbert damping parameters. Potential advantages to using films with lower bubble aspect ratios for ion-implanted circuits are discussed. However nondestructive read-out detection was not realized with these 'flat' bubbles.

Nelson, T. J.↗

NASA NTRS1984

Effective mobility limit in small-bubble, low-damping bubble materials

Examination of the implications of the basic equations that govern the motion of bubbles with nonzero winding number (S) yields an unexpected result. Bubble velocity is limited to the speed implied by the effective wall mobility (gamma)r/2S, no matter how large the actual wall mobility. For large bubbles, this limit will not usually be significant. However, for small bubbles (r less than 1 micron) in low-damping materials, this limit will profoundly affect the bubble motion. A derivation of the effect and experimental confirmation of it are presented.

Slusky, S. E. G.↗