Electrical Spin Injection from Ferromagnetic Nanocontacts into Nondegenerated Silicon at Low Temperatures

• Published in: Journal of superconductivity and novel magnetism Vol. 26; no. 12; pp. 3449 - 3454
• Main Authors: de Araujo, C. I. L., Tumelero, M. A., Avila, J. I., Viegas, A. D. C., Garcia, N., Pasa, A. A.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-12-2013; Springer
• Subjects: Aluminum oxide; Characterization and Evaluation of Materials; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in condensed matter; Electronic transport in multilayers, nanoscale materials and structures; Exact sciences and technology; Magnetic Materials; Magnetic properties and materials; Magnetism; Magnetoresistance; Magnetoresistivity; Nanomaterials; Nanoscale contacts; Nanostructure; Nickel; Original Paper; Physics; Physics and Astronomy; Semiconductors; Silicon substrates; Spin polarized transport; Strongly Correlated Systems; Studies of specific magnetic materials; Superconductivity; Transport properties of condensed matter (nonelectronic); Nondegenerate silicon; Spin injection; Magnetoresistance; Nanocontacts; Aluminium oxide; Elemental semiconductors; Electrical conductivity; Doping; Ferromagnetic materials; Nanostructures; Aluminium Oxides; Lifetime; Spin diffusion; Nickel; Silicon; Diffusion; Diffusion length
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-013-2187-3

We present results on the magnetoresistance of the system Ni/Al
2
O
3
/Si/Al
2
O
3
/Ni fabricated in lateral nanostructures. The substrate n-type Si is a nondegenerated semiconductor with a doping level of 10
15
 cm
−3
. The results are presented between 11 and 30 K, where the electrical resistivity of the semiconductor varies about 4 orders of magnitude. The reduction of magnetoresistance at 30 K is consistent with the standard theory for spin injection between a metal and a semiconductor. By fitting the data with
, the diffusion condition, as a function of the channel length 
t
N
, where the magnetoresistance takes place, we deduced the values of spin diffusion length 
L
SD
and spin lifetime 
τ
s
.