Browse Prior Art Database

Detection of Bubbles by Automation

IP.com Disclosure Number: IPCOM000087852D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 52K

Publishing Venue

IBM

Related People

Argyle, BE: AUTHOR [+3]

Abstract

Magnetic bubble domains of certain types can be made to move using uniform magnetic fields having no spatial gradients. A combination of an in-plane DC magnetic field H(y) and a pulsed z-field h(z)(t) is used to automote the bubble domains.

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Detection of Bubbles by Automation

Magnetic bubble domains of certain types can be made to move using uniform magnetic fields having no spatial gradients. A combination of an in-plane DC magnetic field H(y) and a pulsed z-field h(z)(t) is used to automote the bubble domains.

Fig. 1 shows a sigma(+) domain and a sigma(-) domain, which are S=1 domains. Also shown is an S=0 domain which does not automote in response to the same magnetic fields which will automote the sigma(+) and sigma(-) domains. When the in-plane field H(y) is present together with a modulated z- field pulse h(z)(t) (Fig. 2), the vertical Bloch lines (VBL) move along the domain wall. In the cases of sigma(+) and sigma(-) domains, their reactions combine constructively to impel the sigma(+) and sigma(-) domains in opposite directions. Since the S=0 domain contains two Bloch lines having the same sense of winding, a common direction of circulatory motion of the Bloch lines will be caused, and a cancellation of their gyrotropic reaction forces occurs as a result. Therefore, the S=0 domain does not automote for these excitation fields.

Fig. 2 shows a structure for detecting S=0 and S=1 domains using automotion. In particular, this structure is designed to detect sigma(+) and sigma(-) bubbles. A train of bubbles B moves in the direction of arrow 10 along the guide structure 12. This motion can be produced by a bubble domain pump 14 such as that described in U.S. Patent 3,913,079. The guide structure can be defined by etched grooves in the magnetic material or by a raised portion of the magnetic material in which the domains exist. Additionally, ion implantation or magnetic materials can be use to define the guide structures.

A coil 16 connected to a pulse field current source 18 is used to provide the pulse modulated field h(z)(t). A source (not shown) provides the stabilizing bias field H(b). A further source (not shown) is used to provide the in-plane field H(y).

A gate, comprising conductors 20 and 22, is used to position one domain at a time at the center of coil 16. With no current in conductor 20 and a current toward the left in conductor 22, a domain B' will move to a position between these conductors. Oppositely directed currents in conductors 20 and 22 w...