Detection of an Infrared Magnetorefractive Effect From a Layered Fe/MgO/Fe Magnetic Tunnel Junction

The magnetorefractive effect (MRE) has become an established technique for the contactless measurement of giant and colossal magnetoresistance and has also been extended to the study of thick granular tunnelling films. Here, the MRE is used to study the behaviour of a MgO(100)/Mg0(20 nm)/Fe(20 nm)/MgO(1.5 nm)/Fe(5 nm)/Co(3 nm)/Au(3 nm) magnetic tunnel junction patterned into square pillars of lateral dimension: 50 mum and 5 mum. A significant MRE is observed, enhanced by the presence of an absorption edge associated with MgO, although the exact origin of the effect is unclear.