Magnetic tunnel effect Guide, Meaning , Facts, Information and Description
If two ferromagnets are separated by a thin (about 1 nm) insulator, the resistance of the tunneling current changes with the relative orientation of the two magnetic layers. The resistance is normally higher in the anti-parallel case. This is known as tunnel magnetoresistance (TMR) effect.It was discoverd in 1975 by Julliere [1] , using iron as the ferromagnet and germanium as the insulator.
Room temperature TMR was discovered in 1995 by Moodera et. al. following renewed interest in this field fueled by the discovery of giant magnetoresistance [3,4]. It is now the base for the magnetic random access memory (MRAM). For more technical information see [5].