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31.
对铁电磁体Pb(Fe1/2Nb1/2)O3单晶样品中的 介电和磁性能进行了研究. 认为在其反铁磁相变点观察到的介电常数和损耗的异常来自于自发极化序和自旋序的相互作用 引起的磁电耦合. 磁矩与温度的关系曲线在Nel点以下的低温段呈上升趋势,测得的磁滞 回线证明有弱铁磁性出现. 对铁电磁体磁电相互作用的Monte Carlo模拟得到与实验类似的 结果.
关键词:
铁电磁体
1/2Nb1/2)O3')" href="#">Pb(Fe1/2Nb1/2)O3
磁电耦合
Monte Carlo模拟 相似文献
32.
Critical exponents of ferroelectric transitions in modulated SrTiO3:Consequences of quantum fluctuations and quenched disorder 下载免费PDF全文
The ferroelectric transitions of several SrTiO3-based ferroelectrics are investigated experimentally and theoretically, with special attention to the critical scaling exponents associated with the phase transitions, in order to understand the competition among quantum fluctuations (QFs), quenched disorder, and ferroelectric ordering. Two representative systems with sufficiently strong QFs and quenched disorders in competition with the ferroelectric ordering are investigated. We start from non-stoichiometric SrTiO3(STO) with the Sr/Ti ratio deviating slightly from one, which is believed to maintain strong QFs. Then, we address Ba/Ca co-doped Sr1-x(Ca0.6389Ba0.3611)xTiO3(SCBT) with the averaged Sr-site ionic radius identical to the Sr2+ ionic radius, which is believed to offer remarkable quenched disorder associated with the Sr-site ionic mismatch. The critical exponents associated with polarization P and dielectric susceptibility ε, respectively, as functions of temperature T close to the critical point Tc, are evaluated. It is revealed that both non-stoichiometric SrTiO3 and SCBT exhibit much bigger critical exponents than the Landau mean-field theory predictions. These critical exponents then decrease gradually with increasing doping level or deviation of Sr/Ti ratio from one. A transverse Ising model applicable to the Sr-site doped STO (e.g., Sr1-xCaxTiO3) at low level is used to explain the observed experimental data. It is suggested that the serious deviation of these critical exponents from the Landau theory predictions in these STO-based systems is ascribed to the significant QFs and quenched disorder by partially suppressing the long-range spatial correlation of electric dipoles around the transitions. The present work thus sheds light on our understanding of the critical behaviors of ferroelectric transitions in STO in the presence of quantum fluctuations and quenched disorder, whose effects have been demonstrated to be remarkable. 相似文献
33.
Multiferroic phase transitions in manganites RMnO<sub>3</sub>:A two-orbital double exchange simulation 下载免费PDF全文
The semi-quantum two-orbital exchange model is used to investigate the effect of small rare-earth ion substitution on orthorhombic RMnO 3 with A-type antiferromagnetic order,using the Monte Carlo algorithm,exact diagonalization,and zero-temperature optimization approaches.It is revealed that the substitution results in a rich multiferroic phase diagram where the coexisting A-type antiferromagnetic phase and spiral spin phase,pure spiral spin phase,coexisting spiral spin phase,the E-type antiferromagnetic phase,and the pure E-type antiferromagnetic phase emerge in sequence.The multiferroic phase transitions modulate substantially the electric polarization,which is consistent qualitatively with recent experiments. 相似文献
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Strain-induced insulator–metal transition in ferroelectric BaTiO_3(001) surface:First-principles study 下载免费PDF全文
The electronic properties of TiO_2-terminated BaTiO_3(001) surface subjected to biaxial strain have been studied using first-principles calculations based on density functional theory. The Ti ions are always inward shifted either at compressive or tension strains, while the inward shift of the Ba ions occurs only for high compressive strain, implying an enhanced electric dipole moment in the case of high compressive strain. In particular, an insulator–metal transition is predicted at a compressive biaxial strain of 0.0475. These changes present a very interesting possibility for engineering the electronic properties of ferroelectric BaTiO_3(001) surface. 相似文献
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浪淘沙·文心涨落无欲睹芳容,经典西东。北南风景枉玲珑。正看时光回转后,反演无穷。有意步萍踪,量子匆匆。对角一幕解三重。欲挽本征何处是,简并寒冬。Ⅰ.让声子来存储信息–热导回线在信息领域,热很大程度上是个坏小子。不过,也有时候,热导跟电导一样,是可以利用来存储信息的。与电输运比较,热输运毫无疑问比较慢、比较粗,且热量自由散漫惯了,难以驾驭,也是事实。 相似文献
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<正>无题日行一步当千里,日撰一行作箴言。夜罔冰心勤画月,夜藏拙笔苦为先。I.引子宋代李之仪有诗云:"我住长江头,君住长江尾。日日思君不见君,共饮长江水"。将基础探索与技术应用喻为居于江头和江尾的学科,还算贴切,虽然一定有牵强附会之感。长江源头不过几条冰冻小溪,自下一路万里。这一过程不断有新的形态、组分、蜿蜒曲 相似文献
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Monte Carlo simulation on dielectric relaxation and dipole cluster state in relaxor ferroelectrics 下载免费PDF全文
The Ginzburg--Landau theory on ferroelectrics with random field induced by dipole defects is studied by using Monte Carlo simulation, in order to investigate the dipole configuration and the dielectric relaxation of relaxor ferroelectrics. With the increase of random field, the dipole configuration evolves from the long-range ferroelectric order into the coexistence of short-range dipole-clusters and less polarized matrix. The dipole-cluster phase above the transition temperature and superparaelectric fluctuations far below this temperature are identified for the relaxor ferroelectrics. We investigate the frequency dispersion and the time-domain spectrum of the dielectric relaxation, demonstrating the Vogel--Fulcher relationship and the multi-peaked time-domain distribution of the dielectric relaxation. 相似文献
40.
An elastic Ising model for a one-dimensional diatomic spin chain is
proposed to explain the ferroelectricity induced by the collinear
magnetic order with a low-excited energy state. A statistical theory
based on this model is developed to calculate the electrical and
magnetic properties of Ca3CoMnO6, a typical
quasi-one-dimensional diatomic spin chain system. The calculated
ferroelectric polarization and dielectric susceptibility show a good
agreement with recently reported data on Ca3Co2-xMnxO6 (x ≈0.96) (Phys. Rev. Lett. 100 047601 (2008)), although the predicted magnetic susceptibility
does not coincide well with experiment. We also address the
rationality and deficiency of this model by including a first-order
correction which improves the consistency between the model and
experiment. 相似文献