اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدTranslation domains in multiferroics
108
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Translation domains differing in the phase but not in the orientation of the corresponding order parameter are resolved in two types of multiferroics. Hexagonal (h-) YMnO$_3$ is a split-order-parameter multiferroic in which commensurate ferroelectric translation domains are resolved by piezoresponse force microscopy whereas MnWO$_4$ is a joint-order-parameter multiferroic in which incommensurate magnetic translation domains are observed by optical second harmonic generation. The pronounced manifestation of the generally rather hidden translation domains in these multiferroics and the associated drastic reduction of symmetry emphasize that the presence of translation domains must not be neglected when discussing the physical properties and functionalities of multiferroics.
قيم البحث
اقرأ أيضاً
By using polarized inelastic neutron scattering measurements, we show that the spin-lattice quantum entanglement in mutliferroics results in hybrid elementary excitations, involving spin and lattice degrees of freedom. These excitations can be consid
ered as multiferroic Godstone modes. We argue that the Dzyaloshinskii-Moriya interaction could be at the origin of this hybridization.
We put forward the concept of a bulk Rashba effect emerging in a multiferroic material, such as an antiferromagnetic system with a polar crystal structure. According to symmetry considerations, while time-reversal and space-inversion symmetries are b
oth broken, there exist specific spin flipping operations that relate opposite spin sites in the magnetic crystal structure. As a consequence, at certain high-symmetry points in the momentum space, the magnetic point group allows the spin angular momentum to be locked to the linear momentum, a typical feature of the Rashba effect. In such a case, spin-splitting effects induced by spin-orbit coupling can arise, similar to what happens in non-magnetic Rashba systems. As a prototypical example, ab-initio calculations of antiferromagnetic BiCoO3 in the polar structure reveal that a large Rashba-like band- and spin- splitting occurs at the conduction band bottom, having a large weight from Bi-p orbital states. Moreover, we show that the spin texture of such a multiferroic can be modulated by applying a magnetic field. In particular, an external in-plane magnetic field is predicted not only to induce spin-canting, but also a distortion of the energy isocontours and a shift of the spin-vortex (centered on the high-symmetry point and characteristic of Rashba effect) along a direction perpendicular to the applied field.
We introduce a microscopic model for collinear multiferroics capable to reproduce, as a consequence of magnetic frustration and easy-axis anisotropy, the so-called uudd (or antiphase) magnetic ordering observed in several type II multiferroic materia
ls. The crucial role of lattice distortions in the multiferroic character of these materials is entered into the model via an indirect magnetoelectric coupling, mediated by elastic degrees of freedom through a pantograph mechanism. Long range dipolar interactions set electric dipoles in the antiferroelectric order. We investigate this model by means of extensive DMRG computations and complementary analytical methods. We show that a lattice dimerization induces a spontaneous Z2 ferrielectric bulk polarization, with a sharp switch off produced by a magnetic field above a critical value. The topological character of the magnetic excitations makes this mechanism robust.
We measured the temperature dependences of the static magnetization and the spin excitation in a square-lattice multiferroics Ba$_2$MnGe$_2$O$_7$. An anisotropy gap of the observed low energy mode is scaled by electric polarization rather than a powe
r of sublattice moment. Spin nematic interaction in effective spin Hamiltonian, which is equivalent to interaction of electric polarization, is responsible for the easy-axis anisotropy. The nontrivial behavior of the anisotropy gap can be rationalized as change of the hybridized $d$-$p$ orbital with temperature, leading to the temperature dependence of the spin nematic interaction.
Various phenomena related to inhomogeneous magnetoelectric interaction are considered. The interrelation between spatial modulation of order parameter and electric polarization, known as flexoelectric effect in liquid crystals, in the case of magneti
c media appears in a form of electric polarization induced by spin modulation and vice versa. This flexomagnetoelectric interaction is also related to the influence of ferroelectric domain structure on antiferromagnetic vector distribution, and to the magnetoelectric properties of micromagnetic structures. The influence of inhomogeneous magnetoelectric interaction on dynamic properties of multiferroics, particularly magnon spectra is also considered.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
