IRG 2:
Magnetoelectric Interfaces and Spin Transport
One of the grand challenges in Condensed Matter and Materials Physics (CMMP) research for the next decade, as identified by the National Research Council of the National Academies, is answering the question “How will the information technology revolution be extended?” Further gains in storage capacity and computational power will likely involve approaches other than scaling, and new physical concepts coupled with new functionalities will play a critical role. To address this goal, IRG2 is employing the electron spin in a synergistic combination with novel nanoscale magnetic, magnetoelectric, ferroelectric, and piezoelectric structures to yield new spin-dependent properties and unique functionalities. Novel heterostructures are studied to explore the interplay between electric polarization, elasticity, and magnetism across interfaces to uncover interesting new phenomena, such as electrically-controlled exchange bias and magnetocrystalline anisotropy. Conceptually new kinds of tunnel junctions and magnetic nanocontacts are investigated where a ferroelectric material is used as a barrier layer or as an electric gate material so that electron and spin transport may be manipulated both by electric and magnetic polarizations.
IRG 2 Research Areas:
A. Magnetoelectric and Piezomagnetic Heterostructures
This research is aimed at exploring novel magnetoelectric (ME) and piezomagnetic materials, structures, and phenomena. They are targeted to new interface effects which are studied in well-defined ferromagnetic/ferroelectric (FM/FE) heterostructures. The latter represent the generic basic building block for various novel device concepts where static and dynamic control of ferroic order parameters and their interplay with magnetocrystalline anisotropy determine novel functionalities. We are using complementary approaches to investigate the impact of the FE polarization and piezoelectricity on the FM state in static and dynamic regimes. The electrically controlled exchange bias is investigated using ME antiferromagnets as a pinning layer. Antiperovskite compounds and interfaces are studied, promising new magnetocrystalline anisotropy and piezomagnetic phenomena.
Topics:
- Ferromagnet/Ferroelectric Heterostructures
- Electrically-Controlled Exchange Bias
- Novel Piezomagnetic Materials and Phenomena
B. Magnetoelectric Effects for Spin Transport
This part of IRG2 is aimed at exploring new concepts of spintronics, which involves the manipulation of spin currents through magnetoelectric effects. A FE polarization is employed as a variable to affect the electron and spin transport in novel nanomagnetic structures involving FM/FE interfaces and ferroelectric barriers. Magnetoelectric oxides, resistive switching devices, and magnetic nanojunctions are investigated to uncover new physical phenomena controlling their magnetoresistive and electroresistive properties beneficial for advanced information technologies.
Topics:
- Ferroelectric and Multiferroic Tunnel Junctions
- Electron and Spin Transport in Magnetic Nanojunctions
- Magnetoresistance Switching Phenomena
IRG 2 Highlights:
Journal of Physics: Condensed Matter - Top 20 special issues
(20th anniversary JPCM) (Nov. 2009)
“Half-Metallic Ferromagnets” edited by Peter Dowben
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 Papers 2005
“Magnetoelectronics with Magnetoelectrics” (Ch. Binek and B. Doudin)
Recent IRG 2 Research Highlights:
Electrically Controlled Surface Magnetism
Correlation Effects and Electronic Structure of Gd@C60
Ferroelectrically Controlled Magnetism
IRG 2 Researchers
Christian Binek (coordinator) - Molecular Beam Epitaxy (MBE), magnetic heterostructures, spintronics
Shireen Adenwalla - Nanofabrication, multilayers and e-beam (Neutron Scattering)
Kirill Belashchenko - Electronic structure theory
Peter Dowben - Spectroscopy and surface characterization
Stephen Ducharme - Structural and electrical characterization, Langmuir-Blodgett
Alexei Gruverman - Scanning Probe Microscopy
Jody Redepenning - Chemistry, cluster
Renat Sabirianov - First principles calculations and micromagnetic modeling
Mathias Schubert - Pulsed laser deposition (PLD)
Andrei Sokolov - Nanofabrication, electrical and magnetic characterization
Evgeny Tsymbal - Theory of spin transport and magnetoelectric phenomena
