Magneto-optics film null for magnetic field sensor

摘要

PURPOSE:To obtain the magneto-optical film for sensors which can detect a nonuniformity of slight magnetic fields and micromagnetic fields by epitaxially growing a magnetic garnet film of (GdBi)3(FexAly)O12 on a gadolinium gallium garnet single crystal substrate. CONSTITUTION:The satd. magnetization at about room temp. of the magnetic garnet film is due to the Fe3+ of the d-site and, therefore, if Al+3 of the radius smaller than the radius of the Fe3+ is successively added, the Al3+ substitutes more Al3+ of the d-site than the Fe3+ of the a-side and the satd. magnetization decreases. The matching with a lattice constant is taken when the Al3+ is successively added and, therefore, Bi3+ of a large radius is taken in a large quantity into the magnetic garnet film and a Faraday rotating constant thetaF increases. The compsn. of (GdBi)3(FexAly)O12 is specified to x+y=5 therein and the adequate amt. of the Al to be added is 0.4=y=0.6. The sensitivity coefft. increases when the amt. of the Al to be added is increased. The garnet film 4 and a reflecting film 5 are superposed on the gadolinium gallium garnet single crystal substrate 3 to constitute the sensor element.