Structural features associated with multiferroic behavior in the RX₃(BO₃)₄ system

Abstract

The magnetoelectric effect in the RX 3 (BO 3 ) 4 system (R = Ho, Eu, Sm, Nd, Gd; X = Fe, Al) varies significantly with the cation R despite very similar structural arrangements. Our structural studies reveal a symmetry reducing tilting of the BO 3 planes and of the FeO 6 polyhedra in the systems exhibiting low magnetic field induced electric polarization. Neutron scattering measurements reveal a lack of magnetic ordering indicating the primary importance of the atomic structure in the multiferroic behavior of this system.

Quantum versus classical nature of a low-temperature magnetic phase transition in TbAl$_3$(BO$_3$)$_4$

“…Generally, a physical mechanism proposed must predict not only the decrease of the transition point with increase in B || but the also the other unusual behaviors, like C cr ∼ T y0 and divergence of Γ, found in the present studies. To elucidate the physical mechanism responsible for the transition, detailed neutron diffraction studies are necessary but due to the low transition temperature and the presence of boron, very highly absorbing neutrons, such studies would be very difficult, though possible [11].…”

“…It should be noted that RT 3 (BO 3 ) 4 crystals, with R = Y or rare earth ion and T = Al, Ga, Cr or Fe, attract attention, because they are suitable for laser applications (e.g., aluminoborates doped with Nd are used in self-doubling frequency lasers), show large magnetoelectric effect [10], [11] and different magnetocrystalline anisotropy for various R ions [12]. Thus, deep knowledge of their properties over a wide temperature range is highly desirable.…”

Nature of the structural symmetries associated with hybrid improper ferroelectricity inCa3X2O7(X=Liu1, Zhang2, Ghose3 et al. 2019Phys. Rev. B14090View full textAdd to dashboardCite

“…Accurate structural parameters of Ca [14]). ) For each temperature data set, a systematic space group search was conducted [15].…”

Сравнение спектров поглощения ионов Nd-=SUP=-3+-=/SUP=- в кристаллах NdFe-=SUB=-3-=/SUB=-(BO-=SUB=-3-=/SUB=-)-=SUB=-4-=/SUB=-, Nd-=SUB=-0.5-=/SUB=-Gd-=SUB=-0.5-=/SUB=-Fe-=SUB=-3-=/SUB=-(BO-=SUB=-3-=/SUB=-)-=SUB=-4-=/SUB=- и Ho-=SUB=-0.75-=/SUB=-Nd-=SUB=-0.25-=/SUB=-Fe-=SUB=-3-=/SUB=-(BO-=SUB=-3-=/SUB=-)-=SUB=-4-=/SUB=-

“…Оптические свойства РЗ ионов, а именно f − f переходов, определяются симметрией локального окружения иона. При высоких температурах РЗ ферробораты кристаллизуются в тригональную структуру с пространственной симметрией R32 [10][11][12][13][14]. Элементарная ячейка содержит три формульных единицы.…”

“…Эти октаэдры формируют геликоидальные цепочки вдоль кристаллографической оси C 3 . С понижением темпера-туры некоторые РЗ ферробораты с малыми ионными радиусами РЗ иона претерпевают структурный переход в фазу с пространственной симметрией P3 1 21 [10][11][12]. Это приводит к понижению локальной симметрии РЗ иона до C 2 и появлению двух неэквивалентных позиций ионов Fe 3+ .…”