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Ga(2-x)Fe(x)O(3) As Bubble Domain Material and its Properties

IP.com Disclosure Number: IPCOM000075186D
Original Publication Date: 1971-Aug-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 4 page(s) / 48K

Publishing Venue

IBM

Related People

Giess, EA: AUTHOR [+5]

Abstract

Introduction. Magnetic bubble domain devices require materials with high-bit density and high-bubble domain mobility. Ga(2-x)Fe(x)O(3) compositions, where x varies from 0.7 to 1.4, are suitable for bubble domain device applications because of their magnetic, optic, electric and other properties.

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Ga(2-x)Fe(x)O(3) As Bubble Domain Material and its Properties

Introduction

Magnetic bubble domain devices require materials with high-bit density and high-bubble domain mobility. Ga(2-x)Fe(x)O(3) compositions, where x varies from 0.7 to 1.4, are suitable for bubble domain device applications because of their magnetic, optic, electric and other properties. Specifically, the low 4 Pi M(s) values, the uniaxial anisotropy and the ease of growth of single-crystal films on common substrates such as c-Al(2)O(3) make Ga(2-x)Fe(x)O(3) interesting for bubble domain device. Further, GaFeo(3) has special properties such as its magnetoelectric effect, which permit special logic functions. Illustratively, application of a 3 volt electric field across a 10 mu thick film (E = 3KV/CM) results in a fifty percent decrease in the internal field with doubling of the device data rate at the electrode area. This property can be used to speed up transmission of bubbles around the corners of T-bar arrays, where bubbles are usually slowed down.

Thick single-crystal GaFeO(3) films have been grown by chemical vapor transport techniques involving the transport of Ga and Fe by HCl, followed by oxidation of the chlorides by oxygen. Adjustment of the flow rates of oxygen and HCl resulted in Ga(2-x)Fe(x)O(3) compositions of widely varying stoichiometries. Films with a range of 4 Pi M(s) values have also been realized. Preparation of Ga(2-x)Fe(x)O(3) Epitaxial Films.

The material requirements for bubble domain devices have been discussed in the literature. Briefly, the criteria are:

1) The material should have ferromagnetic curie temperature greater than room temperature.

2) The domain diameter in the material should be in the 1-10 mu range to achieve high-bit densities (>/- 10/6//Sq. inch). For this purpose, the material should have a 4 Pi M(s) value in the low hundreds of gauss.

3) The value of effective anisotropy field (H(k)*) should be only slightly greater than 4 Pi M(s) in order to obtain the best domain wall

4) The thickness of the sample and the bubble domain diameter in it should be equal to 4l and 8l, respectively, where l is the characteristic length; l = sigma(w)/4 pi M/2/(s) where sigma(w) is the 180 degree wall energy and M(s) is the saturation magnetization.

5) Apparently, the sample thickness is half the domain diameter which implies that for high-density applications, the sample thickness should be between 0.5 - 5 mu. Since it is difficult to process bulk material to such small thickness values, it is necessary to grow the material in the form of single crystal thin films by chemical vapor deposition, sputtering or other techniques.

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6) It is preferable not to have exotically substituted material to avoid homogeneity and reproducibility problems.

Some of the properties which make Ga(2-x)Fe(x)O(3) interesting for bubble domain devices are:

1) The orthorhombic structure of Ga(2-x)Fe(x)O(3) is stable over a wide range of compositions, w...