Magnetoresistance of ferromagnetic point junctions from tunneling to direct contact regimes

Author

Pandana, H. ; Gan, L. ; Dreyer, M. ; Krafft, C. ; Gomez, R.D.

Author_Institution

Coll. Park, Univ. of Maryland, College Park, MD, USA

Volume

40

Issue

4

fYear

2004

fDate

7/1/2004 12:00:00 AM

Firstpage

2266

Lastpage

2268

Abstract

The behavior of magnetoresistance in NiFe (permalloy) point junctions was investigated using an STM set-up, where the junction resistance was continuously varied from 10⁸ Ω-10³ Ω. Our results reveal an enhancement of magnetoresistance of more than 80% at one conductance quantum, and the decaying magnetoresistance as one moves away from 12.9 kΩ to either the diffusive regime or the tunneling regime, as supported by independent theories on spin-dependent transport. The suppression of magnetoresistance with incorporation of a 35-nm-thick Au barrier was observed, as well as the dependence of magnetoresistance on the relative orientations of the electrodes.

Keywords

Permalloy; ferromagnetic materials; magnetic tunnelling; magnetoresistance; nickel alloys; scanning tunnelling microscopy; 10E8 to 10E3 ohms; 12.9E3 ohms; 35 nm; NiFe; ballistic magnetoresistance; conductance quantum; decaying magnetoresistance; diffusive regime; direct contact regimes; ferromagnetic point junctions; junction resistance; magnetoresistance enhancement; magnetoresistance suppression; permalloy point junctions; scanning tunneling microscope; spin-dependent transport; tunneling regime; Anisotropic magnetoresistance; Ballistic magnetoresistance; Electromagnets; Gallium nitride; Giant magnetoresistance; Gold; Magnetic sensors; Magnetization; Magnetostriction; Tunneling magnetoresistance; Ballistic magnetoresistance; STM; magnetoresistance; scanning tunneling microscope;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2004.829833

Filename

1325473