Spin-Polarized Resonant Tunneling in Magnetic Tunnel Junctions

• Published in: Science (American Association for the Advancement of Science) Vol. 297; no. 5579; pp. 234 - 237
• Main Authors: Yuasa, S., Nagahama, T., Suzuki, Y.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 12.07.2002; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Applied sciences; Conduction electrons; Copper; Electric potential; Electrodes; Electron tunneling; Electronics; Electrons; Exact sciences and technology; Magnetism; Magnetoelectric, magnetostrictive, magnetoacoustic, magnetooptic and magnetothermal devices. Spintronics; Nanowires; Quantum tunneling; Resonant tunneling; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Tunnel junctions; Tunneling (Physics); Tunnels; Resonant tunnel effect; Barrier layer; Spin polarization; Tunnel junction; Resonant tunneling devices; Magnetoresistance; Spintronics
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1071300

Insertion of a thin nonmagnetic copper Cu(001) layer between the tunnel barrier and the ferromagnetic electrode of a magnetic tunnel junction is shown to result in the oscillation of the tunnel magnetoresistance as a function of the Cu layer thickness. The effect is interpreted in terms of the formation of spin-polarized resonant tunneling. The amplitude of the oscillation is so large that even the sign of the tunnel magnetoresistance alternates. The oscillation period depends on the applied bias voltage, reflecting the energy band structure of Cu. The results are encouraging for the development of spin-dependent resonant tunneling devices.