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

Abstract

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.

Magnetoresistance in thin Permalloy film (10nm thick and 30–200nm wide) nanocontacts fabricated by e-beam lithography

“…For that science and technology needs spintronics units of nanometer size and large changes of voltage drop when the magnetic field is switched. Regarding this point there is a proposal by Garcia and collaborators based in ballistic magnetoresistance (BMR) in atomic contacts (5-7) and nanocontacts (8)(9)(10). There have been challenging that the large MR observed in nanocontact is due to contact modification.…”

Magnetoresistance and Magnetostriction in Magnetic Contacts

“…To our surprise, we have observed even larger values of MR; up to 700% in Ni contacts deposited on small gaps between Ni wires [8] with typical R-values of 5-20 Q. These MR values clearly cannot be explained by DW scattering [9], since the contact sizes are of the order of lOom, while the DW scattering [2,5,9] yields BMR values not larger than 10%.…”

Magnetoresistance of the ferromagnetic nanocontacts fabricated by electrodeposition

“…A 150 nm nano-gap can be clearly seen in this figure. The resistance and the size of the ferromagnetic nanocontacts can be [21], where d is the diameter and R is the resistance of the ferromagnetic nanocontacts. Comparison of the default resistance and the actual resistance, Ni 80 Fe 20 ferromagnetic nanocontacts of a desired size can be fabricated by resistance feedback controlled electroplating.…”