Materials Research Science and Engineering Center

Research - IRG2

IRG 2:

Spin Polarization and Transmission at Nanocontacts and Interfaces

Understanding, controlling and utilizing spin polarization and transport through nanoscale interfaces are major goals for future spintronics technologies. We are using original synthetic methods to fabricate nanoscale magnetic materials and structures, for which enhanced spin-transport properties are expected. In particular, we are investigating magnetoresistive phenomena in magnetic nanocontacts and nanowires, electronic properties of novel ferromagnet/insulator interfaces and junctions with organic ferroelectric barriers. We are studying materials for which the interplay between ferroelectric, magnetic and magnetoelectric properties at the interfaces may reveal new functional properties useful for nanoscale electronic devices. Combined experimental and theoretical expertise helps to uncover new fundamental physical phenomena occurring in these novel heterostructures and interfaces.

IRG 2 Research Areas:

A. Spin Transport in Nanocontacts and Nanowires

Research on magnetic contacts of nanoscale dimensions is of great interest because of the possibility of ballistic electron transport. In particular, our experimental and theoretical work on this topic has uncovered new physics involving Ballistic Anisotropic Magnetoresistance (BAMR). We are investigating spin transport in nanoscale magnetic conductors and tunnel junctions exhibiting resonant tunneling and resistive switching phenomena, affecting magnetoresistive properties. Understanding the physics of these phenomena may lead to new magnetoresistive devices.

Topics:

Spin Transport in Ballistic Nanocontacts
Resonant Tunneling in Magnetic Nanowires
Resistive Switching Effects in Tunnel Junctions
Domain Wall Magnetoresistance

B. Magnetoelectric Interfaces and Ferroelectric Barriers

This work aims at investigating new ferromagnetic/organic systems with potential relevance to spintronics devices and novel physical phenomena related to electron and spin transport across nanoscale ferroelectrics. In particular, we are studying ferroelectric and multiferroic tunnel junctions where electron and spin transport may be controlled by the direction of the electric polarization. Another emphasis is on investigating magnetoelectric interfaces in which magnetic properties may be controlled by applied electric fields and which could yield entirely new device concepts, such as transducers converting between magnetic and electric fields or electric field-controlled magnetic data storage.

Topics:

Organic and Ferroelectric Barrier Layers
Magnetoelectric and Piezomagnetic Interfaces
Ferroelectric and Multiferroic Tunnel Junctions

IRG 2 Highlights:

Journal of Physics: Condensed Matter: Top Papers 2007
(March 2008).

C. N. Borca, D. Ristoiu, H.-K. Jeong, Takashi Komesu, A. N. Caruso, J. Pierre, L. Ranno, J. P. Nozières, and P. A. Dowben, “Epitaxial growth and surface properties of half-metal NiMnSb films,” J. Phys.: Condens. Matter 19, 315211 (2007).
R. F. Sabirianov, W. N. Mei, Jing Lu, Y. Gao, X. C. Zeng, R. D. Bolskar, P. Jeppson, Ning Wu, A. N. Caruso and P. A. Dowben, “Correlation effects and electronic structure of Gd@C₆₀,” J. Phys.: Condens. Matter 19, 082201 (2007).

Journal of Physics: Condensed Matter, Special Issue on “Half-Metallic Ferromagnets” edited by P. A. Dowben (August 2007).

Nature Nanotechnology 2007 paper “Quantized magnetoresistance in atomic-size contacts” (A. Sokolov, C. Zhang, E. Y. Tsymbal, J. Redepenning, and B. Doudin) was featured in Physics World, Materials Today, the Economist, TechWorld, by the Institute of Physics PhysicsWeb, the American Physical Society, and the American Institute of Physics (Feb. 2007).

Physical Review Letters Paper 2006 “Predicted magnetoelectric effect in Fe/BaTiO₃ multilayers: ferroelectric control of magnetism”, by C.-G. Duan, S. S. Jaswal, and E. Y. Tsymbal, was featured by Materials Today.

Journal of Physics: Condensed Matter: Top Paper 2005
“Magnetoelectronics with Magnetoelectrics” (Ch. Binek and B. Doudin)