Magnetoresistive double spin filter tunnel junction

We propose a magnetoresistive tunnel device that takes advantage of the spi n filter effect. Two magnetic tunnel barriers are contacted by normal metal electrodes. The resistance of the device is lower (higher) when the magnet ic moments of the two barriers are parallel (antiparallel). We present a th eoretical calculation of the magnetoresistance. This device has the potenti al to work above room temperature, in very small fields, and to give a sens itivity orders of magnitude larger than what is possible with standard magn etic tunnel junctions. (C) 2000 American Institute of Physics. [S0021-8979( 00)04222-5].