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Functional materials


Phase transitions and properties of ferroics in the form of single crystals, ceramics and thin films II

Ferroic materials undergo a large variety of phase transitions and also exhibit important physical properties, many of which are used in industries world-wide. The study of their phase transitions provides useful ways to understand the origin of the properties, and thus to suggest new materials. Functionality in ferroics can be considered independently on their sizes. They are functional in the macroscopic, microscopic and nanoscopic scales in the form of single crystals, ceramics and thin films. Additionally, the role of controlled content of defects and hence the surface-bulk interrelation makes these materials scientifically exciting and perspective.


Ferroics exhibit strong changes in their properties at a phase transition between a high-symmetry phase, where the material is in a non-ferroic state, and a low-symmetry phase, where the shape of the unit-cell is slightly altered. This breaking of symmetry leads to the appearance of a new physical quantity that can be switched in some way. For instance, the oldest known ferroic property is that of ferromagnetism where magnetization can be switched by an applied magnetic field, leading to magnetic hysteresis. By analogy with ferromagnetism, ferroelectrics are where an electric polarization is switched by an applied electric field, again with hysteresis; and ferroelastics are where strain is switched by an applied stress. These ferroics are known as primary ferroics. One can also have multiferroics where two or more such ferroic properties are present, e.g. magnetization can be switched by an applied electric field, and vice versa. It can be appreciated therefore that ferroics provide a rich field of materials with interesting properties and behaviour, many of which have very important industrial use.

Group-subgroup symmetry changes at phase transitions often define the properties of ferroics. However, changes in micro- and nano-structures are at least as important. It is possible to tune both by changing the form of the material: single crystal, ceramic or thin film. This led to major breakthroughs such as the discovery of unexpected phases and properties at interfaces, as well as giant responses and phase transitions induced by light or electric field. The recent interest for topological structures in ferroics, e.g. domain walls, vortexes, skyrmions, which exhibit their own functionalities and properties, brings a new playground which makes ferroic materials even more scientifically exciting. The symposium will bring together experts working at the theoretical and experimental level.

Hot topics to be covered by the symposium:

  • Structural phase transitions and critical phenomena
  • Magnetoelectric and multiferroic materials
  • Topological structures, domain boundary engineering
  • Interfacial properties, 2D gases
  • Thin films, multilayers and heterostructures
  • Advances in ab-initio calculations and experimental methods
  • Electro/magneto/mechano-caloric effects
  • Flexoelectricity
  • Piezotronics and photo-piezotronics
  • Integration and devices
  • Light-induced phenomena
  • Defects and disorder in ferroics
  • Electronic structure and optical properties
  • Ferroelectrics and antiferroelectrics
  • Piezoelectrics and lead-free piezoelectrics
  • Relaxors and applications
  • Recent advances in electron microscopic study of atomic arrangements
  • Structural aspects of photovoltaic perovskites, organic-inorganic photovoltaic materials

Invited speakers:

  • O. Aktas – Xi'an Jiaotong University, China
  • S. Artyukhin – Italian Institute of Technology, Genova, Italy
  • M. Bibes – Unité Mixte de Physique CNRS/Thales, Palaiseau, France
  • A. Bussmann-Holder – Max-Planck Institute, Stuttgart, Germany
  • D. Damjanovic – Ecole Polytechnique Federale de Lausanne, Switzerland
  • O. Dieguez – Tel Aviv University, Israel
  • B. Dkhil – Ecole Centrale Paris, France
  • M. Trassin – ETH Zürich, Switzerland
  • S. Gorfman – Tel Aviv University, Israel
  • M. Ghidini – University of Parma, Italy
  • P. Ghosez – CESAM, Université de Liège, Belgium
  • M. Gregg – Queen’s University of Belfast, N. Ireland (UK)
  • M. Guennou – University of Luxembourg, Luxembourg
  • J. Hlinka – Czech Academy of Sciences, Prague, Czech Republic
  • S. Gonzalez – Institut des Nanotechnologies de Lyon, France
  • J. Iniguez – Luxembourg Institute of Sciences and Technology, Luxemburg
  • S. Kamba – Czech Academy of Sciences, Prague, Czech Republic
  • A. Klein – TU Darmstadt, Germany
  • J. Koruza – TU Darmstadt, Germany
  • M. Mączka – Polish Academy of Sciences, Wrocław, Poland
  • T. Rojac – Josef Stefan Institute, Ljubljana, Slovenia
  • W. Schranz – University of Wien, Austria
  • J. Schultheiss - Norwegian University of Science and Technology, Norway
  • C. Toulouse – University of Luxembourg, Luxembourg
  • R. McQuaid – Queen's University Belfast, N. Ireland (UK)
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Authors : J. M. Gregg
Affiliations : Queen's University Belfast

Resume : Partial switching of ferroelectric lithium niobate thin films causes the injection of 180 degree domain walls which are initially strongly inclined with respect to the polarisation axis. Strong inclination angles mean a significant polar discontinuity across the domain wall that is associated with dramatically enhanced electrical conductivity. In the first part of this talk, the magnetotransport behaviour of these conducting walls will be reported. The naturally formed conical domain structures allow for geometrical magnetoresistance behaviour analogous to that seen in Corbino Discs, allowing direct access to carrier mobility values. Such mobilities are extremely large - of the order of thousands of cm2V-1s-1. We believe them to be the highest room temperature values seen in any oxide system to date. In the second part of the talk, the manner in which domain wall morphology and conductance can be altered by applied fields and wall relaxation after field removal will be presented. It will be shown that complex kinetics and associated conduction variations allow for both neuromorphic and conventional memory-related functionality to be generated.


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Symposium organizers
Anthony Michael GLAZERUniversity of Oxford

Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK
Guillaume NATAFCentre National de la Recherche Scientifique (CNRS)

University laboratory GREMAN, France
Krystian ROLEDERInstitute of Physics | University of Silesia

Uniwersytecka 4 40-007 Katowice Poland

+48 32 359 1478
Marek PAŚCIAKInstitute of Physics, Czech Acad. Sci.

Na Slovance 2, 182 21 Prague 8, CZ