Spin filtering and an enhanced regime of giant magnetoresistance

Citation
Ms. Ferreira et al., Spin filtering and an enhanced regime of giant magnetoresistance, J PHYS-COND, 12(12), 2000, pp. 2833-2846
Citations number
26
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF PHYSICS-CONDENSED MATTER
ISSN journal
09538984 → ACNP
Volume
12
Issue
12
Year of publication
2000
Pages
2833 - 2846
Database
ISI
SICI code
0953-8984(20000327)12:12<2833:SFAAER>2.0.ZU;2-E
Abstract
A new regime of magnetoresistance (MR) in systems composed of magnetic laye rs separated by non-magnetic modulated structures is studied. The ability t o tailor the electronic structure of superlatticed systems enables one to e ngineer contrasting spin-dependent transport properties, enhancing the magn etoresistance ratios. When the system acts as a spin filter the MR ratios r each values many orders of magnitude larger than those of conventional gian t magnetoresistance. Rather than a mere enhancement of the magnetoresistanc e ratios, this new regime involves ingenious combinations of spin-polarized currents. Moreover, it results from a magnetic-field-induced metal-insulat or transition along the modulation direction, characterizing a highly aniso tropic transport behaviour. The existence of an insulating phase circumvent s the experimental challenge of probing excessively small resistances in th e current-perpendicular-to-plane (CPP) geometry of magnetoresistance. A pic ture in terms of the hulk Fermi surfaces of the constituent materials emerg es and provides general guidelines on how to achieve this regime.