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Nanosecond Camera for Garnet Bubble Domain Dynamics

IP.com Disclosure Number: IPCOM000078612D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Malozemoff, AP: AUTHOR

Abstract

To study the dynamics of domains in magnetic bubble materials, a high-speed photographic technique is often desirable. Rossol/1/ developed a stroboscopic technique able to resolve events up to 7 MHz and has applied it to domain dynamics in orthoferrites. However, in the more recent garnet bubble materials, many dynamic processes occur at higher speeds requiring 10 ns time resolution; also higher spatial resolution is required, since domains are often 5 mu m or less in diameter. Therefore, garnet dynamics have been studied primarily either by indirect techniques such as Bobeck's bubble collapse method,/2/ or by electronic techniques such as monitoring the bulk magnetization changes/3/ or the Faraday response/4,5/.

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Nanosecond Camera for Garnet Bubble Domain Dynamics

To study the dynamics of domains in magnetic bubble materials, a high- speed photographic technique is often desirable. Rossol/1/ developed a stroboscopic technique able to resolve events up to 7 MHz and has applied it to domain dynamics in orthoferrites. However, in the more recent garnet bubble materials, many dynamic processes occur at higher speeds requiring 10 ns time resolution; also higher spatial resolution is required, since domains are often 5 mu m or less in diameter. Therefore, garnet dynamics have been studied primarily either by indirect techniques such as Bobeck's bubble collapse method,/2/ or by electronic techniques such as monitoring the bulk magnetization changes/3/ or the Faraday response/4,5/.

However, Kryder and Humphrey/6/ have demonstrated the feasibility of 10 ns photography for permalloy films. They used a 10 MWatt pulsed ruby laser and a Kerr magneto-optic shutter to resolve domains via the longitudinal Kerr effect. The purpose of this description is to show that 10 ns photography with high magnification can also be achieved for garnet bubble materials.

A schematic of the apparatus is illustrated above. A cell of 0.001 molar rhodamine 6G dye in ethanol is pumped transversely by an Avco Model C950 nitrogen laser/7/. With a diffraction grating and a half-silvered mirror, the cell can be made to emit a 30 kWatt pulse of less than 10 ns duration at 5800 Angstroms with 10 Angstrom bandwidth. The light pulse is introduced into a standard polarizing microscope (a Leitz Ortholux), with the usual polaroid filters (no special precautions necessary). The light is focused below the sample so as to illuminate an area of roughly 100 mu m/2/. Caution must be exercised not to focus the beam directly onto the garnet film to avoid damaging it. Under typical operating conditions, the t...