Topological excitations in ferroelectrics for the ultrafast low-energy nanoelectronics

Igor Lukyanchuk 1,*

1 Laboratory of Condensed Matter Physics, University of Picardie, France

* lukyanc@ferroix.net

 

Formation of unusual textures of polarization is imminent for nano-scale ferroelectric samples, films, rods, and granules, where the depolarization surface effects play the crucial role. The topologically protected stability of such textures is coming from polarization vorticity, provided by condition of the absence of the energetically-unfavorable depolarization charge. We consider the unconventional topological polarization textures in several nano-scale systems, in which they were either already directly observed or can be yet discovered, and discuss their applications in the emergent oxide-based nanoelectronic devices.

Polarization domains that alternate the surface charge distribution, first proposed by Landau (1935) and Kittel (1946) in contents of ferromagnetism can be formed in ferroelectric thin films as an effective mechanism to confine the depolarization field to the near-surface layer and diminish the depolarization energy. However their existence have long been considered as barely possible until recent direct theoretical predictions [1,2] and experimental evidences [3-5] in thin oxide-based superlattices.  Very recently we have demonstrated that the few-nanometer thick PbTiO3/SrTiO3 superlattices with periodic domain structures exhibit the striking feature. The effective capacitance of ferroelectric layers is negative [6]. This effect is explained by the opposite orientation of the depolarizing field with respect to the field-induced averaged polarization. This phenomenon is currently considered as the platform for realization of the dissipation-free high performance nano-circuits [7]. Moreover, in sub-THz region the real part of the dielectric constant becomes positive, passing through zero at frequency ~0.3-3THz, inducing the resonance effect, suitable for design of the ultra-small low-energy THz chips.

• and skyrmion states are formed inside ferroelectric cylindrical nano-dots and nanorods to reduce the depolarization energy. We study the stability of such states and calculate the phase diagram of the system. We demonstrate that the topological class of the most stable topological excitations can be driven by the geometrical and electrical parameters of the system, external field and temperature. We target the multi-domain and topological excitations in FE nanodots as a platform for multivalued logic units, breaking ground for neuromorphic computing [8].

 

V. A. Stephanovich, I. A. Luk'yanchuk, and M. G. Karkut,, Phys. Rev. Lett.,  94 047601 (2005)I. Luk'yanchuk, L. Lahoche, and A. Sene, Phys. Rev. Lett., 102, 147601 (2009) S. K. Streiffer, J. A. Eastman, D. D. Fong et al., Phys. Rev. Lett. 89, 067601 (2002); S. O. Hruszkewycz, M. J. Highland, et al., Phys. Rev. Lett.110, 177601 (2013).Yadav, A. K., Nelson,et al.. Nature, 530 (7589), 198. (2016) P. Zubko, M. Hadjimichael, S. Fernandez-Pena, A. Sené, I. Luk’yanchuk, J.-M. Triscone & J. Íñiguez, Nature, 534, 524 (2016) Khan, A. I., Chatterjee, K., Wang B. et al. Nature Materials 14, 182–186 (2015).Baudry, L., Lukyanchuk, I. & Vinokur, V. M. Nature Sci. Rep. 7: 42196 (2017)

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BIOGRAPHIE:

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Professor Igor Lukyanchuk graduated from the Moscow Physico-Technical Institute – MFTI, and, after graduation, joined the theory group in Landau Institute for Theoretical Physics. During his research career he had a unique opportunity to collaborate with the world-famous creators of modern Solid State Theory. Their guidelines idea of the predominant fundamental Physical Principles helps him further to switch easily between such different objects as superconductors, magnetic materials, fullerenes, ferroelectrics etc, to profit the generality of theoretical approaches and easily collaborate with experimentalists.

Working hereafter in Germany (91-92), Brazil (96-99), Swiss (2000) and in France (since 2001), he always tried to follow these high research and teaching standards, keeping the close relations with other world-spread members of Landau School and maintaining his status of the Associated Member of Landau Institute.

Being the leader of the theory group in his laboratory and creating the compact inter-university modeling group in North of France, he arrived to occupy the important niche in the world research in ferroelectric domains. To follow the trends of the rapidly varying scientific world he maintains the collaborative links with the famous scientific centers: ILL-Grenoble, HP-Labs (Palo Alto, CA), University of Cambridge, Unicamp-Brazil, Argone National Laboratory. These collaborations led, in particularly to identification of Dirac Fermions in Graphite, the precursor of the “Graphene boom” and corresponding Nobel Prize.

Coordination of collaboration with different European Countries is another important part of his activity. A number of FP7 and H2020 European projects and networks were organized under his supervising. In 2004, he initiated and directed the very original set of biannual “International Meetings on Materials or Electronic Applications – IMMEA” that has the objective to gather the fundamental and applied researchers, working on different aspects of material physics in European and Maghreb Research Areas. Beyond this, Professor Lukyanchuk organized a series of advanced research and training workshops on fundamental and applied physics, under the guidance of such famous founding organization as NATO, ICTP-UNESCO, Mediterranean Institute for Fundamental Physics (MIFP) and International Institute of Physics IIP-Natal. The world-famous researchers, working on appropriate aspects of material physics were invited and involved in the training activity.

Believing in the necessity of high-level research in academic media, professor Lukyanchuk is trying to use all his knowledge and expertise to select the quality, competence and long-range recruiting strategy as decisive criteria of scientific policy.