Fe掺杂到BaTiO 3中,稳定了顺电六方相,代替了铁电四氢呋喃[P. P. et al. Phys. Rev. B,101,064409(2020)]。我们发现,同时掺杂的Bi和Fe到钛酸钡有效地提高了磁电(ME)多铁性响应(铁磁性和铁电性)在室温下,通过仔细调整的Fe价态,随着控制恢复的铁电性,四相。随着Bi掺杂量的增加,Ba_(1-x)Bi_xTi_(0.9)Fe_(0.1)O_3(0<x<0.1)样品的介电常数随温度的变化逐渐增大,介电损耗角正切值逐渐减小,这使得Bi-Fe共掺杂量较高的样品(x=0.08)有望用作室温高k介电材料。有趣的是,x=0.08(Bi-Fe共掺杂)样品不仅被发现在室温下比x=0(仅掺杂Fe)强铁电性(~20倍)和铁磁性(~6倍),而且还观察到更好的绝缘性(更大的带隙),具有更大的ME耦合的间接特征,如从磁矫顽场随着温度降低的异常减少所指示的。因此,室温ME多铁性已被设计在Bi和Fe共掺杂的BTO(钛酸钡)化合物。
英文摘要:
Fe doping into BaTiO3, stabilizes the paraelectric hexagonal phase in place of the ferroelectric tetragonal one [P. Pal et al. Phys. Rev. B, 101, 064409 (2020)]. We show that simultaneous doping of Bi along with Fe into BaTiO3 effectively enhances the magnetoelectric (ME) multiferroic response (both ferromagnetism and ferroelectricity) at room-temperature, through careful tuning of Fe valency along with the controlled-recovery of ferroelectric-tetragonal phase. We also report systematic increase in large dielectric constant values as well as reduction in loss tangent values with relatively moderate temperature variation of dielectric constant around room-temperature with increasing Bi doping content in Ba1-xBixTi0.9Fe0.1O3 (0<x<0.1), which makes the higher Bi-Fe codoped sample (x=0.08) promising for the use as room-temperature high-k dielectric material. Interestingly, x=0.08 (Bi-Fe codoped) sample is not only found to be ferroelectrically (~20 times) and ferromagnetically (~6 times) stronger than x=0 (only Fe-doped) at room temperature, but also observed to be better insulating (larger bandgap) with indirect signatures of larger ME coupling as indicated from anomalous reduction of magnetic coercive field with decreasing temperature. Thus, room-temperature ME multiferroicity has been engineered in Bi and Fe codoped BTO (BaTiO3) compounds.
Emergence of strong room-temperature ferroelectricity and multiferroicity in 2D-Ti$_3$C$_2$T$_x$ free-standing MXene film
二维(2D)多铁性材料是智能技术发展的关键候选材料。在这里,我们采用了一种简单的合成方法来实现人们期待已久的开发铁电和多铁性2D材料的梦想,特别是在称为MXenes的新型材料中。蚀刻的Ti $_3$ C $_2$ T $_x$ MXene首先在HF处理之后合成,然后进行分层工艺以成功合成自支撑Ti $_3$ C $_2$ T $_x$膜。然后将自支撑膜在室温下暴露于空气以及在不同温度下加热以形成衍生自Ti $_3$ C $_2$ T $_x$ MXene本身的TiO $_2$层。TiO $_2$是一种初期铁电材料,具有复合铁电相。结构和形貌分析证实了自支撑膜的成功合成,拉曼光谱揭示了不同相的TiO $_2$的形成。铁电体的测量表明,在室温下的一个明确的极化滞后回线。此外,在薄膜中观察到的磁滞表明在室温下的铁电和铁磁相之间的耦合的可能性。还进行了磁电耦合测试,其显示在施加的磁场下的清晰的、可切换的自发极化。这是首次报道室温下二维自支撑MXene薄膜中存在铁电相和多铁性耦合,这开辟了室温下基于二维材料的电和磁数据存储应用的可能性。
Strain-Induced Relaxor Multiferroicity at Room Temperature in Hexaferrite BaFe12O19 Thin Films
Cornell University(康奈尔大学);The Pennsylvania State University(宾夕法尼亚州立大学);Leibniz-Institut für Kristallzüchtung(莱布尼兹晶体生长研究所);Oak Ridge National Laboratory(橡树岭国家实验室);University of Tennessee(田纳西大学);University of California, Berkeley(加州大学伯克利分校);University of North Texas(北德克萨斯大学);University of Southern California(南加州大学);Kavli Institute at Cornell for Nanoscale Science(康奈尔纳米科学卡弗里研究所)
Local multiferroic ordering at room temperature in collinear magnetoelectric antiferromagnets induced by flexo-Zeeman coupling
Helmholtz-Zentrum Dresden-Rossendorf e.V.(德累斯顿-罗森多夫亥姆霍兹中心);Faculty of Physics of Dresden University of Technology(德累斯顿工业大学物理学院);Helmholtz-Zentrum Berlin für Materialien und Energie(柏林亥姆霍兹材料与能源中心);Department of Applied Physics, KTH Royal Institute of Technology(瑞典皇家理工学院应用物理系)
Multiferroicity in the two-dimensional limit in hexagonal LuFeO3 films
Fudan University(复旦大学);University of Science and Technology Beijing(北京科技大学);Brookhaven National Laboratory(布鲁克海文国家实验室);Hefei National Laboratory(合肥国家实验室);Shanghai Research Center for Quantum Sciences(上海量子科学研究中心);Zhangjiang Fudan International Innovation Center(张江复旦国际创新中心);University of Nebraska, Lincoln(内布拉斯加大学林肯分校)
Above room temperature multiferroic tunnel junction with the altermagnetic metal CrSb
Huazhong University of Science and Technology(华中科技大学);Florida State University(佛罗里达州立大学);National High Magnetic Field Laboratory(国家强磁场实验室);Charles University(查理大学)