A. Magnetoelectric and Multiferroic Nanostructures

This research theme focuses on the exploring of novel phenomena in multiferroic nanostructures. 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
• Electrically Controllable Boundary Magnetization

B. Magnetoelectric Effects for Spin Transport

This research theme focuses on the exploring of 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
• Ferroelectric-Enhanced Organic Electronics

» Science 2012
H. Lu, C.-W. Bark, D. Esque de los Ojos, J. Alcala, C. B. Eom, G. Catalan, and A. Gruverman, "Mechanical Writing of Ferroelectric Polarization," Science 6, 59-64 (2012). Featured on NSF Discoveries web page.
Listen to Alexei Gruverman's interview on the April 6th Science podcast.

» Nature Materials 2012
Evgeny Tsymbal “Spintronics: Electric Toggling of Magnets”, Nature Materials 11, 12-13 (2012) .

» Nature Materials 2011
Y. Yuan, T. J. Reece, P. Sharma, S. Poddar, S. Ducharme, A. Gruverman, Y. Yang, and J. Huang, “Efficiency enhancement in organic solar cells with ferroelectric polymers,” Nature Materials 10, 296-302 (2011).

» Nano Letters 2011
A. Mardana, S. Ducharme, and S. Adenwalla, “Ferroelectric Control of Magnetic Anisotropy,” Nano Letters 11 (9), 3862-3867 (2011).

» Invited MRS Review 2011
E. Y. Tsymbal, A. Gruverman, V. Garcia, M. Bibes, and A. Barthélémy, : “Ferroelectric and Multiferroic Tunnel Junctions,” MRS Bulletin 37, 138-43 (2012).

» Physical Review Letters 2011
N. Wu, X. He, A. L. Wysocki, U. Lanke, T. Komesu, K. D. Belashchenko, C. Binek, and P. A. Dowben, “Imaging and control of surface magnetization domains in a magnetoelectric antiferromagnet,” Phys. Rev. Lett. 106, 087202 (2010).

» Nature Materials 2010
Xi He, Yi Wang, Ning Wu, Anthony N. Caruso, Elio Vescovo, Kirill Belashchenko, Peter Dowben, and Christian Binek, "Robust isothermal electric control of exchange bias at room temperature"
Nature Materials 9, 579-585 (2010). Featured on NSF Discoveries web page.

» Physical Review Letters 2010
K. D. Belashchenko, "Equilibrium Magnetization at the Boundary of a Magnetoelectric Antiferromagnet" Phys. Rev. Lett. 105, 147204 (2010).

» Nature Materials 2009
Stephen Ducharme and Alexei Gruverman “Ferroelectrics: Start the presses” Nature Materials 8, 9-10 (2009).

» Journal of Physics: Condensed Matter - Top 20 special issues (20th anniversary JPCM) (Nov. 2009)
“Half-Metallic Ferromagnets” edited by Peter Dowben

» Nano Letters 2009
A. Gruverman, D. Wu, H. Lu, Y. Wang, H. W. Jang, C. M. Folkman, M. Ye. Zhuravlev, D. Felker, M. Rzchowski, C.-B. Eom and E. Y. Tsymbal,"Tunneling Electroresistance Effect in Ferroelectric Tunnel Junctions at the Nanoscale," Nano Lett. 9 (10), 3539–3543 (2009). (Nanowerk News)