Ballistic magnetoresistance in a magnetic nanometer sized contact:: An effective gate for spintronics

We present experimental results of unprecedented large magnetoresistance obtained in stable electrodeposited Ni-Ni nanocontacts 10-30 nm in diameter. The contacts exhibit magnetoresistance of up to 700% at room temperature and low applied fields and, therefore, act as very effective spin filters. These large values of the magnetoresistance are attributed to spin ballistic transport through a magnetic "dead layer" at the contact of width of about 1 nm or smaller. Nanometer sized, high sensitive magnetoresistive sensors could become key elements for magnetic storage in the terabit/in.(2) range and in high density magnetic random access memories. (C) 2001 American Institute of Physics.