Related papers: Macroscopic polarization from nonlinear gradient c…
Multiferroic materials exhibit the coexistence of magnetic and electric order. They are at the forefront of modern condensed matter physics due to their potential applications in next-generation technologies such as data storage, sensors,…
We introduce microscopic polarization and magnetization fields at each site of an extended system, as well as free charge and current density fields associated with charge movement from site to site, by employing a lattice gauge approach…
Using classical Monte Carlo simulations, we study a simple statistical mechanical model of relevance to the emergence of polarisation from local displacements on the square and cubic lattices. Our model contains two key ingredients: a…
Working in the crystal-momentum representation, we calculate the optical conductivity of noncentrosymmetric insulating crystals at first order in the wave vector of light. The time-even part of this tensor describes natural optical activity…
Light fields at THz and mid-infrared frequencies allow for the direct excitation of collective modes in condensed matter, which can be driven to large amplitudes. For example, excitation of the crystal lattice, has been shown to stimulate…
Ferroelectric properties of cubic chiral magnet Cu2OSeO3 can emerge due to the spin noncollinearity induced by antiferromagnetic cantings. These cantings are the result of the Dzyaloshinskii-Moriya interaction and in many ways similar to…
The spin-driven component of electric polarization in a single crystal of multiferroic BiFeO$_{3}$ was experimentally investigated in pulsed high magnetic fields up to 41 T. Sequential measurements of electric polarization for various…
A systematic microscopic theory of magnetically induced ferroelectricity and lattice modulation is presented for all electron configurations of Mott-insulating transition-metal oxides. Various mechanisms of polarization are identified in…
We carry out first-principles density-functional-theory calculations to elucidate the polarization switching mechanism in charge-ordering-induced ferroelectrics based on the prototypical case of the (SrVO$_3$)$_1$(LaVO$_3$)$_1$…
Recent advances in moire engineering provide new pathways for manipulating lattice distortions and electronic properties in low-dimensional materials. Here, we demonstrate that twisted stacking can induce dipolar vortices in metallic SrRuO3…
Understanding of the intimate cross-coupling between electric and magnetic degrees of freedom in solids usually requires sophisticated models and time-consuming calculation methods. Instead of macroscopic symmetry analysis, we present a…
Pyrochlore magnets are a paradigmatic example of three-dimensional frustrated systems and provide an excellent platform for studying a variety of exotic many-body phenomena, including spin liquids, nematic phases, fragmentation, and order…
A microscopic model for the room-temperature multiferroic BiFeO$_3$ that includes two Dzyaloshinskii-Moriya interactions and single-ion anisotropy along the ferroelectric polarization predicts both the zero-field spectroscopic modes as well…
This manuscript deals with the question "How does light couple to an antiferromagnetic order parameter"? For that we develop a microscopic model that explains the non-reciprocal optical effects in centrosymmetric Cr_2 O_3. It is shown that…
Magneto-optic behaviour is a specific, non-reciprocal example of gyrotropic behaviour. When coupled to photo-induced Faraday rotation it is possible to discriminate this effect from the background of other nonlinear effects Non-reciprocal…
In the review we briefly analyze the state-of-art in the theory of flexoelectric phenomena and analyze how significantly the flexoelectric coupling can change the polar order parameter distribution in different ferroics and liquid crystals.…
We examine density ordered and superfluid phases of fermionic dipoles in a two-dimensional square lattice at non-zero temperature. The critical temperature of the density ordered phases is determined and is shown to be proportional to the…
Tuning the lattice degree of freedom in nanoscale functional crystals is critical to exploit the emerging functionalities such as piezoelectricity, shape-memory effect, or piezomagnetism, which are attributed to the intrinsic lattice-polar…
This paper represents a detailed instruction manual for constructing the Landau expansion for magnetoelectric coupling in incommensurate ferroelectric magnets. The first step is to describe the magnetic ordering in terms of symmetry adapted…
We review the phenomenology of coupled magnetic and electric order parameters for systems in which ferroelectric and incommensurate magnetic order occur simultaneously. We discuss the role that such materials might play in fabricating novel…