The ERC project will provide material design strategies that can remove the stringent lattice matching criteria to stack different classes of layered materials and provide these class of layered materials with similar stacking freedom as layered materials with vdWIs. These insights will allow the interbreeding of different classes of layered quantum materials, such as complex oxides, 2D layered crystals with vdWIs, cuprate superconductors or topological insulators or semimetals.

The possibility to create new materials bottom-up was enhanced via the stacking of atomically thin layers of two-dimensional (2D) materials with van der Waals interactions (vdWIs). Unfortunately, the downside of vdWIs is the, in general, weak electronical and mechanical interaction between the individual layers. This hinders the creation of multiferroic materials working at ambient conditions, which are despite extensive research still very scarce, from stacked layers with vdWIs.
This research aims to create a new 2D building block: the 2D sandwich. This is a layered heterostructure with a strong interaction between the sandwich's individual layers mediated via an ionic or multivalent bond, whereas the interaction with other layers is still solely due to the vdWIs. As the prototype functional material, a 2D magnetoelectric multiferroic sandwich composed of layered transition metal chalcogenides, oxides or iodides will be grown using the modulated elemental reactants method.
To tackle the possible sample degradation in the sandwiches, ultra-high vacuum optical surface science spectro-microscopy techniques will be developed to optically probe the 2D multiferroic sandwiches for both magnetism, ferroelectricity and the coupling between them. The concept of open samples will be introduced, facilitating the scientific community with the straightforward verification of the data and accelerate the development of this new class of 2D sandwiches.
This project will provide material design strategies that can remove the stringent lattice matching criteria to stack different classes of layered materials and provide these class of layered materials with similar stacking freedom as layered materials with vdWIs. These insights will allow the interbreeding of different classes of layered quantum materials, such as complex oxides, 2D layered crystals with vdWIs, cuprate superconductors or topological insulators or semimetals.

On the trail of novel spintronic and electronic devices via exotic light-matter interactions

Topological states are exotic phases of matter resistant to change. They give rise to phenomena such as crystals that insulate on the inside but conduct electricity on their surfaces (topological insulators) or chiral arrangements of some order parameters in real space. It is also possible to isolate individual topological entities and use them for specific tasks, especially for information technology purposes. The EU-funded TSAR project will investigate topological phenomena in 'unconventional' topological materials where the staggered orders (electric and magnetic) result in a macroscopic cancellation of their built-in fields. This will open new horizons in the manipulation of individual topological solitons at very fast speed.

With the end of Moore’s law in sight, new schemes must be devised to achieve energy efficient, high density and high-speed data storage and processing. One emerging concept in today’s condensed-matter physics that may fuel next-generation information technology is topology. Topological phenomena in real space can give rise to interesting objects (for instance magnetic skyrmions), which are topologically protected, i.e. endowed with an energy barrier associated with a change in their topology class. These solitonic objects have been found mainly in magnetic materials like ferromagnets and there are very recent reports that ferroelectrics may also be able to host them. Interestingly, antiferroic orders like antiferromagnetism or antiferroelectricity would provide extra properties, e.g. a faster motion or an increased robustness. In TSAR, we will design antiferroic systems based on oxide materials where spin and electric dipole textures will be nucleated. We will devise approaches to control these topological solitons using different stimuli, and in particular ultra-fast vortex light pulses carrying angular orbital momentum. Gathering a consortium with broad expertise comprising academic (experimental and theoretical groups) and industrial partners, strategies will be devised and applied starting from high quality materials to devices. The targeted breakthrough of our project is to realize the first proof-of-concept for agile, low-power, room-temperature spintronic and electronic devices based on antiferroic topological materials. Their intrinsic high speed operation and low-power consumption will help tackling present societal challenges. Success in these endeavors will establish topological antiferroic systems as a novel versatile platform for future energy-efficient nanoelectronics.

Novel magnetoelectric liquid material could revolutionise sensing

The magnetoelectric (ME) effect, discovered in the 1960s, enables engineers to control electric properties with a magnetic field and vice versa. The only known ME materials to date are solid-state multiferroics, which are under intense study and development for applications in revolutionary memory technologies, and spintronic devices. On the other hand, solid-state piezolelectrics have been exploited in force sensing devices, enabling very high sensitivity to detect small changes, resulting in excellent resolution. While solid ME materials are well-suited to 'hard' devices, imagine the 'flexibility' – literally and practically – of liquid ME materials. The EU-funded MAGNELIQ project will develop a new liquid material, a ME liquid, and novel sensors that could be used in human-like devices from robotics to prostheses.

Our radical vision of a science-enabled technology is a magneto-electric (ME) liquid for new devices like distributed-force sensors that can transform complex structures like the skins of humanoid robots and artificial body parts. A ME material is characterised by having magnetic properties that can be manipulated with an electric field and, vice versa, electric properties that can be manipulated with a magnetic field. Until now the only ME materials have been solid-state mutliferroics, because until recently ferroic properties were considered to be specific to solid materials. However, based on our recent discovery of ferromagnetic liquids, which overturned this established paradigm, we propose a breakthrough liquid ME material. The basic component of this ME liquid will be ME nanoplatelets (NPs), i.e. magnetic NPs that will be hybridized with electrically polarized organics. These ME-NPs will then be dispersed in a nonconductive liquid medium, where they will be able to reorient in an external field. At volume concentrations of >10 vol.% ME-NPs multiferroic liquids will be formed and characterized by a simultaneous spontaneous polarization and magnetization without an externally applied field. A new surface-selective hybridization technology will be developed together with the synthesis of electrically polarized organics for the fabrication of the ME-NPs. The ME liquids will be realised with an all-new multiscale modelling framework; the chemical interactions and physical properties of an individual magnetic NP with organic ligands will require ab-initio calculations; and phenomenological models will account for the complex interactions between all the system phases, including the system’s interaction with external fields. The envisioned ME-liquids-enabling technologies will surpass current sensing paradigms by providing contactless and remote operation, low energy consumption, wireless signal transmission, distributed sensing and miniaturization.

Producing energy from renewable sources imposes challenges related to storing a constantly fluctuating energy. The development of innovative materials for high-energy storage with good temperature stability is therefore essential for applications in electric vehicles, aeronautics, geothermal energy exploitation, etc. Nowadays, no material completely meets the current industrial requirements. Recent models describing the energy density and efficiency of antiferroelectric materials provide an encouraging guidance towards achieving good storage properties in small, light, inexpensive, and environmentally-friendly components. In this interdisciplinary bilateral Czech-Slovenian project we propose to develop new environment-friendly, lead-free relaxor antiferroelectric materials and to design proof-of-concept multilayer capacitors on the basis of lattice-dynamics and structure-property characterization of materials across multiple length-scales, supported by simulations and modelling.

The project is focused on development of multi-functional hybrid colloids based on liquid crystalline compounds and magnetic nanoparticles to open new perspectives for applications in energy storage systems or smart sensors.

Modern dielectric materials with exceptional electromechanical response are based on perovskite solid solutions in the composition range of the morphotropic phase boundary (MPB). Despite their importance for applications, the explanation of their performance is elusive, as it is hard to access the real short-range atomic order experimentally and accurate calculations of finite-temperature properties with current models are challenging. We propose a comprehensive approach combining multiscale modeling and experiment. We engage first-principle techniques to design interatomic potentials fine-tuned for the atomic order in MPBs, which will be determined experimentally using the recently developed anomalous diffuse scattering method. Molecular-dynamics simulations of large enough structures will provide direct insight into the local structure-property relationship. Potentials for various cation species will enable to develop a high-throughput screening scheme and design of new, environmentally-friendly materials. The best candidates will be synthesized and characterized.

The project is focused on verification of recent theories that THz-pumping of polar phonons can induce transient ferroelectricity or even magnetization in diamagnetic paraelectrics. The measurements will be performed on quantum paraelectrics KTaO3 and (EuSrBa)TiO3. We will also study influence of strain on lattice dynamics and magnetic exchange coupling in thin films of various transition metal monoxides with the aim to prepare strain-induced multiferroics in highly strained superlattices of MnO with other magnetic monoxides. Static and dynamic magnetoelectric coupling in various multiferroics will be also studied in radiofrequency, microwave and THz region.

Excitation of carriers in graphene nanostructures leads to the formation of terahertz plasmons. The plasmonic response in graphene is intrinsically nonlinear and ultrafast. It features strong field confinement and is governed by the quasi-Fermi level dynamics (and thus by the temperature of carriers). The manipulation and control of plasmons is promising for integrated opto-electronics (namely for THz detection and sensing) with speeds well beyond the gigahertz regime. We will develop various devices based on gated graphene meta-surfaces that will allow us to manipulate the plasmons by the sample morphology and by optical, electrical, and chemical routes to attain full control over their behavior. The concerted use of near-field (local probe) and far-field time-resolved THz spectroscopic techniques will provide a terahertz readout of the charge carrier state, of plasmon resonances, their hotspots, and decays.

The main objective of new collaborative Czech-Taiwanese project proposal is three-fold. Czech team will design and characterize new functional photoactive self-organizing materials possessing the liquid crystalline (LC) behaviour which can be suitable as (i) smart dopants for tuning the power conversion efficiency of photovoltaic cells or (ii) photonic devices. Taiwanese team will develop new complex-shape discotic functionalized materials possessing the columnar phases that can form well-defined supramolecular structure. Beyond high application potential of both structurally different classes of self-organizing materials, the project will contribute to better understanding of the molecular architecture – mesomorphic property relationship and will reinforce long lasting collaboration by effective and multidisciplinary knowledge transfer. The complementarity of the teams is very strong and this project is truly interdisciplinary; hence its results will have impact on chemistry and physics of self-organizing materials but also will advance soft matter chemistry, physics and photonics.

Electron transport in nanostructures frequently exhibits quantum signatures, which may be advantageous for the design of novel types of nanometer-sized electronic devices. We propose to identify, observe and characterize a potentially strong quantum effect: electron tunneling between semiconductor nanoparticles over a nanometer-sized gap, induced by the plasmon resonance at THz frequencies. Unlike in metals, the period of plasmon oscillation in a semiconductor nanoparticle is much longer than the tunneling time, therefore we aim at exploration of a coupling mechanism not yet described in the literature. We will consider a prototypical system of two coupled nanoparticles and we will develop a theoretical model for its description, including energy quantization, tunneling and field enhancement close to the nanoparticle surface. Quantitative interpretation of the spectra measured using THz scattering SNOM technique with high spatial and temporal resolution will be developed to facilitate a direct comparison with the theoretical models.

The spread of wearable devices is pushing the need for compact photonic elements with advanced light control functionality and recent development show, that Blue Phase (BP) liquid crystals have a promising future in such photonic devices. The project aims to obtain large 3D photonic crystals based BP liquid crystal structures, with controlled crystal orientation and photonic properties designed for topologically protected spatial lasing, light switching, and holography. This project is a joint effort focusing on:
(i) understanding the alignment mechanism of BPs through the development of new materials,
(ii) preparing large 3D photonic crystals based on BPs,
(iii) applying new materials in actual photonic devices: a laser microcavity, an all-optical tunable crystal, and a holographic element.

The project is truly interdisciplinary as the research teams, consisting of material scientists (PL), chemists and physicists (CZ) and external collaborators applied physicists (JP) will pursue new materials and ideas to develop protocols to direct self-assembly of BP photonic crystals on demand.

Self-organisation and chirality are common in nature. However, utilizing inherent chirality of chiral molecules to operate molecular machines or to imprint new materials properties by light may address key challenges of current technology. One possible way to assure and strengthen the chiral light-chiral material interaction is to use supramolecular systems possessing macroscopic chirality. The main aim is to design smart supramolecular chiral self-organizing materials with helix length close to the visible light wavelength; this can assure contactless control and tuning of their behaviour by direct matter-light interaction. Specifically, new chiral mesogenic materials, chiral dopants with build-in functionality, like photo-activity and luminescence, will be developed to gain the systematic knowledge on the molecular architecture – nano-organization relationship for the above mentioned photosensitive supramolecular systems. Expected outcomes of the project are not only of high fundamental interest but also very vital for the foreseen specific practical applications.

The physical properties of many systems, ranging from naturally occurring biopolymers to artificial materials, often crucially depend on those global features that cannot be ascribed to a particular geometry or arrangement, rather to a more abstract notion: topology. The latter manifests itself in the knotted state of proteins and artificial polymers, the intertwining among DNA rings, or the topologically distinct classes of defect lines that can be found in liquid crystals. A better understanding of the interplay between a system’s topological state, its three-dimensional structure, and its overall characteristics paves the way to an improved control of relevant natural molecules or human-made materials, with remarkable impact on fundamental science as well as high-tech applications. These goals, however, can only be achieved through a multidisciplinary effort, involving a wide spectrum of expertise in a concerted manner.
The EUTOPIA COST Action will establish a collaborative platform to approach all those problems, in the study of biological and soft matter, that feature topological characteristics. In doing this, it will create a pan-European, synergistic network of researchers from different fields that will overcome geographical, economical and societal barriers, as well as those naturally surrounding traditional academic communities. The outcomes of the research carried out thanks to the EUTOPIA Action will push forward the boundaries of our current understanding of key systems, and foster the knowledge transfer of scientific findings to industry and, ultimately, to society as a whole.

The overall aim of this project for scientific collaboration between Czech and Polish teams is to acquire knowledge on unique self-organisation ability of liquid crystalline systems and to contribute to understanding of molecular architecture – nano-organization relation, which is of fundamental interest but also a starting point for future applications in opto-electronics and photonics.
The main specific objectives of the project are:
(I) to design and to study new low molar mass materials of various structures exhibiting the polar mesophases with ferroelectric and antiferroelectric (FLC) order over a broad temperature range (mostly PL team).
(II) to design new photosensitive liquid crystalline dopants (PD) with photosensitive moieties (mainly the azoxy-group) and to study their properties and structures under external stimulus, like electric field or/and UV irradiation by X-ray scattering, dielectric spectroscopy and electro-optics (mostly CZ team).
(III) to design binary and/or multicomponent photosensitive mixtures and composites (FLC+PD) responding the demands of specific applications in photonics and optoelectronics and to study and to tune their properties; special attention will be given to the operating temperature range of the FLC+PD composites and to appropriate value of the refractive indices suitable for technological processes (both CZ & PL teams).
(IV) to acquire a systematic information on molecular architecture – nano-organization relationship for all the above mentioned types of supramolecular photosensitive systems, which are of high fundamental interest but also as a starting point for future applications in photonics and opto-electronics (both CZ & PL teams).
Strong complementarity of the CZ & PL team members, their experience and experimental facilities as well as efficient experience in past collaborative projects should assure the success while reaching the project objectives.

This work aims to obtain and characterize physico-chemically Phase Change Materials (PCMs) with improved chemical and thermal stability for thermal energy storage in buildings with nearly zero energy consumption. Once obtained, the PCMs will be tested in the laboratory modules with various geometry as a preliminary step for implementing them in the thermally energy storage systems for buildings.

The recently discovered coexistence of both ferroelectricity and non-conventional skyrmionic spin textures in the lacunar spinel GaV₄S₈ (GVS) promises outstanding magnetoelectric effects to happen in these compounds. Notably, GVS is the first and only multiferroic material known to date that potentially might find its way into top-modern applications such as skyrmionic memories. In order to significantly advance the fundamental understanding, we propose in this bilateral project to shed light onto the fundamental static and dynamic behavior of GVS and its related compounds, through the concerted nanoscale approach between theory and experiment. More precisely, we uniquely combine the local-scale experimental inspection (by using various scanning probe techniques and optical spectroscopy) with multi-scale modeling strategies (i.e. ab-initio, phase field modelling, etc.). The two participating teams in Prague/Czech Republic and Dresden/Germany form the ideal basis in order to conduct this research in the proposed bilateral project.

The proposed project will promote a close collaboration between Prague and Dresden teams interested in a same hot research topic of peculiar vortex phases in multiferroic materials. In order to bridge different experimental (Dresden team) and theoretical (mainly Prague team) approaches used in our teams, we plan mutual workshops, training sessions for PhD students and discussion of recent results. We believe that the developed synergy between our teams and a unique combination of the local-scale experimental inspection (by using various scanning probe techniques and optical spectroscopy) with multi-scale modeling strategies (i.e. ab-initio, phase field modelling, etc.) will significantly advance the fundamental understanding to, for example an outstanding magnetoelectric effect in GaV₄S₈, which is the first and only multiferroic material known to date that potentially might find its way into top-modern applications such as skyrmionic memories.

The project will study the high frequency ferroelectric response (mainly above 1 MHz) and lattice dynamcs of several relaxor and ferroelectric materials, in order to understand the important microwave range (1-100 GHz), where relaxation processes at the mesoscale takes place. This is important to understand the conection between macroscopic properties, like permittivity, and the microscopic atomic structure. We will focus in iniaxial relaxor materials like SrBaNb₂O₆ and similar, but also in ferroelectrics based on BaTiO₃ and PbTiO₃, because all of them show responses in the 10-100 GHz range, that were not properly studied and understood up to now. The experiences and techniques of our department and the partner organization will complement to cover the broad band multiexperimental approach needed.

The project is focused on verification of recent theories that THz-pumping of polar phonons can induce transient ferroelectricity or even magnetization in diamagnetic paraelectrics. The measurements will be performed on quantum paraelectrics KTaO₃ and (EuSrBa)TiO₃. We will also study influence of strain on lattice dynamics and magnetic exchange coupling in thin films of various transition metal monoxides with the aim to prepare strain-induced multiferroics in highly strained superlattices of MnO with other magnetic monoxides. Static and dynamic magnetoelectric coupling in various multiferroics will be also studied in radiofrequency, microwave and THz region.

Domain walls in ferroelectrics are naturally formed 2D solitons with a defined, nm-thick polarization profile stable over macroscopic lateral dimensions. Strong coupling of the polarization gradient with strain drastically changes the material properties within the domain wall thickness. Increasing attention is paid to these mobile interfaces because the characterization tools have recently reached the desired nanoscale resolution, needed to uncover the rich spectrum of new phenomena expected there. We are convinced that some ferroelectrics can also host 1D analogues of domain walls, i.e. spontaneously formed ferroelectric line solitons, similar to the recently experimentally confirmed Bogdanov-Yablonskitype magnetic skyrmion lines. We wish to extend the explorations also to these interesting topological objects and to pave a path to the experimental discovery of the ferroelectric skyrmion phases, analogous to the vortex states in superconductors and skyrmion phases of chiral magnets.

Charged domain walls in ferroelectric materials are accompanied by a high density of charges screening the jump in the polarization. This causes fundamental changes in the electronic structure close to the domain wall; it was even anticipated that magnetic moments can be induced in otherwise non-magnetic materials. This effect was indeed observed in ferroelectrics containing charges e.g. due oxygen vacancies. We propose to search for magnetic properties induced by various charge carriers also in charged domain walls in ferroelectrics: this would enable us to achieve magneto-electric coupling and controlled operations thanks to the domain walls motion. To this aim, we will combine electron and scanning probe microscopies for micro-scale characterization, magnetization measurements, thermal noise and conventional impedance spectroscopy for sensing macro-scale properties, with calculations using the phenomenological Landau-Ginzburg-Devonshire theory. This will allow us to obtain a detailed picture of the electronic and magnetic structure of charged domain walls in ferroelectrics.

Water molecules separated by distances in the order of nanometres cannot form hydrogen bonds. Then, the dipole-dipole interaction plays a major role, inducing a dynamical behavior of water very different from the liquid phase. Such a situation occurs in specific crystals containing water of crystallization; there, the water response can be additionally altered by the hydration degree. The interactions lead to collective motions of water molecules which we will study by a set of methods of broadband dielectric spectroscopy. Within the project, we will explain the links between the spatial arrangement of water molecules and their collective dynamical response. As predicted theoretically, the dipole-dipole interaction may lead to ferroelectric ordering of water molecules accompanied by a mesoscopic electric field. Similar orderings could play a key role in various natural processes, e.g., influence the heterogeneous ice nucleation in nature. The project will enable us to predict configurations allowing the ferroelectric ordering, and, possibly, to prove this ordering experimentally.

Relaxor behaviour occurs in chemically-substituted ferroelectrics due to the disruption of the long-range correlation of cation displacements. Substitution can be performed either with homovalent or heterovalent cations. Then either non-polar regions are created in the polar lattice matrix, or polar defect complexes are formed, respectively. These non-polar or polar Polarization Decorrelation Regions (POLDERs) have different correlation length and can respond differently to the applied electric fields. In heterovalent-substituted (non chargecompensated) Ba-based perovskites, relaxor behaviour appears for much lower substituent contents than in homovalent-substituted ones (e.g. at 7 wt.% substituent content against 35 wt.%, respectively). It is vital to study the formation, distribution and interaction of polar and nonpolar POLDERs on the nano- to mesoscale in order to tune macroscopic dielectric properties in these relaxors. This project for the first time will study the role of POLDERs in disrupting longrange ferroelectricity.

Ageing of the population has led to an increasing need for bone and joint tissue replacements. Novel types of alloys have been developed, together with modifications to the physicochemical properties of the surface to accelerate the osseointegration of bone implants. The creation of electrically-active surfaces is a promising approach. The aim of the project is to provide solutions to problems of osseointegration that often arise in orthopaedic surgery. Permanent bone implants from titanium alloy (screws), including 3D-printed titanium with a trabecular structure, will be covered with electrically-active surfaces to support osseointegration of artificial materials into the bones. The osteogenic potential of the ferroelectric layers will be tested in vitro (in static culture and using mechanical loading of the samples seeded with bone-derived cells). Markers of cell adhesion, growth and differentiation will be evaluated. The most promising coating will be tested in vivo. The implants will be inserted into the femur of miniature pigs, and histological analyses will be performed.

The ability to tune molecular self-organization at nano- and meso-scopic length scales with an external stimulus is the main driving force in bottom-up nanofabrication of molecular devices. Liquid crystalline materials are able to self-assemble into smart supramolecular structures with desirable functionality and physical properties. While modifying the molecular structure, such systems can become responsive towards mechanical stress, light, electric or magnetic fields. The target photochromic structures will be varied among bent-shaped, hockey-stick and rod-like molecules with chiral and non-chiral chains, reactive mesogens and macromolecular materials. The main objective is to design new smart supramolecular photosensitive self-assembling materials of two types:

1. with a stabilized Z-form aimed for memory devices design;
2. with fast response on UV irradiation can be successfully used in photonics.

Quantum coherence in systems with electron correlations will be studied by means of Green functions, renormalized many-body theory, and numerical simulations. We will extend an approximation earlier developed by us with a two-particle self-consistency from the reduced parquet equations qualitatively correctly describing the Kondo strong-coupling limit of the metallic dot. The general theory will be applied to a model of quantum dot attached to superconducting leads with the aim to explain and understand its behavior at the transition from the spin singlet to the spin doublet state (zero-pi transition). The dot will be studied in an applied weak magnetic field in order to understand this transition and the properties of the spin doublet state with a degenerate ground state. The magnetic solution in a consistent theory must continuously match the non-magnetic one in the limit of the vanishing field. We further extend the static approximation from the reduced parquet equations to a dynamical one to make it applicable to low-dimensional lattice systems with long-range quantum coherence.

We study quantum coherence induced by electron correlations in microscopic models of hybrid nano-scale and low-dimensional bulk superconductors. We will use both analytic methods and numerical simulations to achieve a better understanding of impurity quantum phase transitions and the zero-temperature superconductivity in two-dimensional systems.

Using broadband dielectric and phonon spectroscopies, we will study the lattice and spin dynamics of multiferroics near their structural and magnetic phase transitions. We will investigate static and dynamic magnetoelectric couplings in multiferroics with Y- and Z-hexaferrite structures, in Ni_3-x(Co, Mn)_xTeO₆ (x = 1, 2), Mn₃WO₆, Cu₃Nb₂O₈ and AMn₇O₁₂ (A = Sr, Pb, Cd). These materials exhibit different crystalline and magnetic structures, so their magnetoelectric couplings will have different origins. Our data will allow us to explain the origin of static and dynamic magnetoelectric couplings. We will perform time-resolved THz-pump, THz probe experiments, which will allow for studying the dynamics of electromagnons and changes of magnetic structures on a sub-picosecond scale. We will also strive to achieve the first observation of a theoretically predicted phonon Zeeman effect; for this we will use EuTiO₃ which exhibits a strong spin-phonon coupling. Using THz and Raman spectroscopies, we will investigate the tuning of electromagnons frequencies in electric and magnetic field.

Organic-inorganic hybrid nanostructures are promising candidates for a new class of materials with properties not observed for individual components. The aim of the project is to develop new approaches for nanostructured system preparation. Particular interest will be devoted to organic supramolecular structures and paramagnetic liquid crystalline compounds, preparation of ligands followed by functionalization of magnetic nanoparticles. Other nanoparticles (ferroelectric, up-converting, etc.) will be considered for mixing with liquid crystalline structures to create new types of hybrid composites. We expect distinct optical, magnetic and dielectric properties, which can be tuned by temperature and concentration changes and changed by external stimuli (magnetic or electric field).