"Electronically Driven Interface Magnetoelectric Effects "

Evgeny Y. Tsymbal

Department of Physics and Astronomy, University of Nebraska--Lincoln

Controlling magnetic properties by electric fields through a magnetoelectric (ME) effect has recently attracted significant interest due to interesting physics involved and new functionalities not available in conventional devices. Especially attractive are ferromagnet/ insulator interfaces where the ME effect may have purely electronic origins. Spin-dependent screening of an electric field is predicted to change the surface magnetization and the surface magnetocrystalline anisotropy.1,2 ME effects may be enhanced at ferromagnet/insulator interfaces if the insulator has a large dielectric constant. A particular example of the Fe/MgO(001) interface demonstrates a sizable effect of electric fields on the surface magnetocrystalline anisotropy consistent with recent experiments. Even a more significant enhancement may be achieved at the ferromagnet/ferroelectric interface where the reversal of the ferroelectric polarization produces notable changes in the interface magnetization3,4,5 and the interface magnetocrystalline anisotropy.6 In addition to screening, the ME coupling may be induced by changing the overlap between atomic orbitals at the interface that affects the interface magnetization. For a different system, namely a La1/2Ba1/2MnO3/BaTiO3 heterostructure, we predict a new type of the interface ME effect, originating from the modulation of the charge density in La1/2Ba1/2MnO3 by the polarization reversal of BaTiO3.7 This effect manifests itself in the change of the magnetic order at the interface from ferromagnetic to antiferromagnetic. This talk will address these and other interface ME phenomena based on our recent first-principles and model calculations.

1. C.-G. Duan et al., Phys. Rev. Lett. 101 137201 (2008).
2. C.-G. Duan et al., Phys. Rev. B 79, R140403 (2009).
3. C.-G. Duan et al., Phys. Rev. Lett. 97, 047201 (2006).
4. M. K. Niranjan et al., Phys. Rev. B 78, 104405 (2008).
5. M. K. Niranjan et al., Appl. Phys. Lett. 95, 052501 (2009).
6. M. K. Niranjan et al., Appl. Phys. Lett. 92, 122905 (2008).
7. J. D. Burton and E. Y. Tsymbal, Phys. Rev. B 80, 174406 (2009).