Low birefringent orthoferrites for optical devices

Abstract

Nonmagnetic optical birefringence for light propagated along the direction of magnetization can be reduced to low levels in orthoferrite compositions such as Nd <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Pr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> FeO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> . This results in a significant improvement in Faraday rotation detection of magnetic domains in thin single crystal orthoferrite platelets. For a simple two polarizer detection scheme, one can obtain light transmitted in the ON state of 10-20 percent of the incident light for contrasts between the ON and OFF states of greater than 20/1, for He-Ne laser light at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\lambda = 0.633 \mu</tex> m and for platelet thicknesses of 0.001- 0.003 in. The low birefringent orthoferrites can be used in optical memory and display devices employing mobile magnetic bubble domains or reversible localized domains which act as binary optical shutters.