Resonant electron tunnelling assisted by charged domain walls in multiferroic tunnel junctions

Article metrics


The peculiar features of domain walls observed in ferroelectrics make them promising active elements for next-generation non-volatile memories, logic gates and energy-harvesting devices. Although extensive research activity has been devoted recently to making full use of this technological potential, concrete realizations of working nanodevices exploiting these functional properties are yet to be demonstrated. Here, we fabricate a multiferroic tunnel junction based on ferromagnetic La0.7Sr0.3MnO3 electrodes separated by an ultrathin ferroelectric BaTiO3 tunnel barrier, where a head-to-head domain wall is constrained. An electron gas stabilized by oxygen vacancies is confined within the domain wall, displaying discrete quantum-well energy levels. These states assist resonant electron tunnelling processes across the barrier, leading to strong quantum oscillations of the electrical conductance.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Quantum oscillations of the tunnelling conductance.
Figure 2: Cross-sectional scanning transmission electron microscopy images of a La0.7Sr0.3MnO3/BaTiO3 superlattice.
Figure 3: Unit cell mapping of the ferroelectric polarization displacements and the electronic state in the BTO layer.
Figure 4: Electronic structure of the head-to-head domain wall.
Figure 5: Switching of the ferroelectric polarization of the barrier.


  1. 1

    Velev, J. P. et al. Magnetic tunnel junctions with ferroelectric barriers: prediction of four resistance states from first principles. Nano Lett. 9, 427–432 (2009).

  2. 2

    Garcia, V. et al. Giant tunnel electroresistance for non-destructive readout of ferroelectric states. Nature 460, 81–84 (2009).

  3. 3

    Gruverman, A. et al. Tunneling electroresistance effect in ferroelectric tunnel junctions at the nanoscale. Nano Lett. 9, 3539–3543 (2009).

  4. 4

    Maksymovych, P. et al. Polarization control of electron tunneling into ferroelectric surfaces. Science 324, 1421–1425 (2009).

  5. 5

    Wen, Z., Li, C., Wu, D., Li, A. & Ming, N. Ferroelectric-field-effect-enhanced electroresistance in metal/ferroelectric/semiconductor tunnel junctions. Nat. Mater. 12, 617–621 (2013).

  6. 6

    Yin, Y. W. et al. Enhanced tunnelling electroresistance effect due to a ferroelectrically induced phase transition at a magnetic complex oxide interface. Nat. Mater. 12, 397–402 (2013).

  7. 7

    Garcia, V. et al. Ferroelectric control of spin polarization. Science 327, 1106–1110 (2010).

  8. 8

    Chanthbouala, A. et al. A ferroelectric memristor. Nat. Mater. 11, 860–864 (2012).

  9. 9

    Farokhipoor, S. et al. Artificial chemical and magnetic structure at the domain walls of an epitaxial oxide. Nature 515, 379–383 (2014).

  10. 10

    Sluka, T., Tagantsev, A. K., Bednyakov, P. & Setter, N. Free-electron gas at charged domain walls in insulating BaTiO3. Nat. Commun. 4, 1808 (2013).

  11. 11

    Sluka, T., Tagantsev, A. K., Damjanovic, D., Gureev, M. & Setter, N. Enhanced electromechanical response of ferroelectrics due to charged domain walls. Nat. Commun. 3, 748 (2012).

  12. 12

    Crassous, A., Sluka, T., Tagantsev, A. K. & Setter, N. Polarization charge as a reconfigurable quasi-dopant in ferroelectric thin films. Nat. Nanotech. 10, 614–618 (2015).

  13. 13

    Han, M.-G. et al. Interface-induced nonswitchable domains in ferroelectric thin films. Nat. Commun. 5, 4693 (2016).

  14. 14

    Catalan, G., Seidel, J., Ramesh, R. & Scott, J. F. Domain wall nanoelectronics. Rev. Mod. Phys. 84, 119–156 (2012).

  15. 15

    Seidel, J. et al. Conduction at domain walls in oxide multiferroics. Nat. Mater. 8, 229–234 (2009).

  16. 16

    Salje, H. E. K. Multiferroic domain boundaries as active memory devices: trajectories towards domain boundary engineering. ChemPhysChem 11, 940–950 (2010).

  17. 17

    Miaoa, G.-X. et al. Inelastic tunneling spectroscopy of magnetic tunnel junctions based on CoFeB/MgO/CoFeB with Mg insertion layer. J. Appl. Phys. 99, 08T305 (2006).

  18. 18

    Jia, C.-L. et al. Atomic-scale study of electric dipoles near charged and uncharged domain walls in ferroelectric films. Nat. Mater. 7, 57–61 (2008).

  19. 19

    Jia, C. & Urban, K. Atomic-resolution measurement of oxygen concentration in oxide materials. Science 303, 2001–2004 (2004).

  20. 20

    Kim, Y., Jeong, J., Kim, J. & Kim, Y. Image processing of atomic resolution transmission electron microscope images. J. Korean Phys. Soc. 48, 250–255 (2006).

  21. 21

    Chang, H. J. et al. Atomically resolved mapping of polarization and electric fields across ferroelectric/oxide interfaces by Z-contrast imaging. Adv. Mater. 23, 2474–2479 (2011).

  22. 22

    Wang, Y., Liu, X., Burton, J. D., Jaswal, S. S. & Tsymbal, E. Y. Ferroelectric instability under screened Coulomb interactions. Phys. Rev. Lett. 109, 247601 (2012).

  23. 23

    Jia, C.-L. et al. Unit-cell scale mapping of ferroelectricity and tetragonality in epitaxial ultrathin ferroelectric films. Nat. Mater. 6, 64–69 (2007).

  24. 24

    Chisholm, M. F., Luo, W., Oxley, M. P., Pantelides, S. T. & Lee, H. N. Atomic-scale compensation phenomena at polar interfaces. Phys. Rev. Lett. 105, 197602 (2010).

  25. 25

    Yoshiya, M., Tanaka, I., Kaneko, K. & Hadachi, H. First principles calculation of chemical shifts in ELNES/NEXAFS of titanium oxides. J. Phys. Cond. Mat. 11, 3217–3228 (1999).

  26. 26

    Kolodiazhnyi, T., Tachibana, M., Kawaji, H., Hwang, J. & Takayama-Muromachi, E. Persistence of ferroelectricity in BaTiO3 through the insulator–metal transition. Phys. Rev. Lett. 104, 147602 (2010).

  27. 27

    Adler, S. B. Chemical expansivity of electrochemical ceramics. J. Am. Ceram. Soc. 84, 2117–2119 (2001).

  28. 28

    Aschauer, U., Pfenninger, R., Selbach, S. M., Grande, T. & Spaldin, N. A. Strain controlled oxygen vacancy formation and ordering in CaMnO3 . Phys. Rev. B 88, 054111 (2013).

  29. 29

    Calleja, M., Dove, M. & Salje, E. K. H. Trapping of oxygen vacancies on twin walls of CaTiO3: a computer simulation study. J. Phys. Condens. Matter 15, 2301–2307 (2003).

  30. 30

    Seidel, J. et al. Domain wall conductivity in La-doped BiFeO3 . Phys. Rev. Lett. 105, 197603 (2010).

  31. 31

    Kim, Y.-M. et al. Probing oxygen vacancy concentration and homogeneity in solid-oxide fuel-cell cathode materials on the subunit-cell level. Nat. Mater. 11, 888–894 (2012).

  32. 32

    Xiao, Y., Shenoy, V. B. & Bhattacharya, K. Depletion layers and domain walls in semiconducting ferroelectric thin films. Phys. Rev. Lett. 95, 247603 (2005).

  33. 33

    Duan, C.-G., Sabirianov, R. F., Mei, W.-N., Jaswal, S. S. & Tsymbal, E. Y. Interface effect on ferroelectricity at the nanoscale. Nano Lett. 6, 483–487 (2006).

  34. 34

    Wang, Y. et al. Ferroelectric dead layer driven by a polar interface. Phys. Rev. B 82, 094114 (2010).

  35. 35

    Yu, P. et al. Interface control of bulk ferroelectric polarization. Proc. Natl Acad. Sci. USA 109, 9710–9715 (2012).

  36. 36

    Wu, X. & Vanderbilt, D. Theory of hypothetical ferroelectric superlattices incorporating head-to-head and tail-to-tail 180° domain walls. Phys. Rev. B 73, 020103 (2006).

  37. 37

    Santander-Syro, A. F. et al. Two-dimensional electron gas with universal subbands at the surface of SrTiO3 . Nature 469, 189–193 (2011).

  38. 38

    Varela, M. et al. Direct evidence for block-by-block growth in high temperature superconductor ultrathinfilms. Phys Rev. Lett. 86, 5156–5159 (2001).

  39. 39

    Visani, C. et al. Symmetrical interfacial reconstruction and magnetism in La0.7Ca0.3MnO3/YBa2Cu3O7/La0.7Ca0.3MnO3 heterostructures. Phys. Rev. B 84, 060405 (2011).

  40. 40

    Garcia-Barriocanal, J. et al. ‘Charge leakage’ at LaMnO3/SrTiO3 interfaces. Adv. Mater. 22, 627–632 (2010).

  41. 41

    Bruno, F. Y. et al. Electronic and magnetic reconstructions in La0.7Sr0.3MnO3/SrTiO3 heterostructures: a case of enhanced interlayer coupling controlled by the interface. Phys. Rev. Lett. 106, 147205 (2011).

  42. 42

    Malik, V. K. et al. Pulsed laser deposition growth of heteroepitaxial YBa2Cu3O7/La0.67Ca0.33MnO3 superlattices on NdGaO3 and Sr0.7La0.3Al0.65Ta0.35O3 substrates. Phys. Rev. B 85, 054514 (2012).

  43. 43

    Bosman, M., Watanabe, M., Alexander, L. D. T. & Keast, V. J. Mapping chemical and bonding information using multivariate analysis of electron energy-loss spectrum images. Ultramicroscopy 106, 1024–1032 (2006).

  44. 44

    Ghosez, P., Michenaud, J. & Gonze, X. Dynamical atomic charges: the case of ABO3 compounds. Phys. Rev. B 58, 6224–6240 (1998).

  45. 45

    Stoyanov, E., Langenhorst, F. & Steinle-Neumann, G. The effect of valence state and site geometry on Ti L3,2 and O K electron energy-loss spectra of TixOy phases. Am. Mineral. 92, 577–586 (2007).

  46. 46

    Kresse, G. & Hafner, J. Ab initio molecular dynamics for liquid metals. Phys. Rev. B 47, 558–561 (1993).

  47. 47

    Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).

  48. 48

    Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).

  49. 49

    Dudarev, S. L., Botton, G. A., Savrasov, S. Y., Humphreys, C. J. & Sutton, A. P. Electron-energy-loss spectra and the structural stability of nickel oxide: an LSDA+U study. Phys. Rev. B 57, 1505–1509 (1998).

  50. 50

    Okamoto, S., Millis, A. J. & Spaldin, N. A. Lattice relaxation in oxide heterostructures: LaTiO3/SrTiO3 superlattices. Phys. Rev. Lett. 97, 056802 (2006).

  51. 51

    Li, J. C., Beltrán, J. I. & Carmen Muñoz, M. Multiorbital structure of the two-dimensional electron gas in LaAlO3/SrTiO3 heterostructures. The formation of a d xy ferromagnetic sheet. Phys. Rev. B 87, 075411 (2013).

Download references


Work supported by Spanish MINECO through grants MAT2014-52405-C02-01 and MAT2014-52405-C02-02, MAT2015-066888-C3-1-R, MAT2015-066888-C3-3-R (MINECO/FEDER) and CAM S2013/MIT-2740. The authors thank M. Watanabe for the Digital Micrograph PCA plug-in and A. Lupini for the atomic column mapping scripts. Research at ORNL sponsored by the US Department of Energy (DOE), Basic Energy Sciences (BES), M.V. acknowledges support from Fundación BBVA. G.S. and M.C. acknowledge support from ERC Starting Investigator Grant #239739 STEMOX. J.I.B. acknowledges the Spanish Supercomputing Network (RES) and CeSViMa (project FI-2016-2-0006). J.S. thanks Université Paris Saclay (DÁlembert Program) and CNRS for financing his stay at CNRS Thales.

Author information

J.S. conceived and designed the experiments, discussed and analysed data and wrote the manuscript. J.T. grew the samples and performed transport experiments. D.H.-M., M.C., Z.S. and A.P.-M. helped with growth and transport experiments and discussed results. C.L. discussed and set up experiments, analysed transport data and helped write the manuscript. G.S.-S. and M.V. performed microscopy experiments. S.J.P. and M.V. analysed microscopy data and helped write the manuscript. M.C.M., J.I.B. and D.H.-M. performed and analysed the density-functional theory calculations. M.C.M. helped write the manuscript. C.M., F.M., J.R. and M.G.-H. performed piezoresponse force microscopy experiments. All authors discussed the results and commented on the manuscript.

Correspondence to Jacobo Santamaria.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 1139 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Sanchez-Santolino, G., Tornos, J., Hernandez-Martin, D. et al. Resonant electron tunnelling assisted by charged domain walls in multiferroic tunnel junctions. Nature Nanotech 12, 655–662 (2017) doi:10.1038/nnano.2017.51

Download citation

Further reading