Tuning order from disordered ground states in geometrically frustrated classical "non-hbar" materials

从几何受挫经典“非 hbar”材料中的无序基态调整顺序

• 批准号: EP/M01052X/1
• 负责人: Chris Stock
• 金额: $ 93.27万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FM01052X%2F1
• 关键词: Tuning; order; disordered; ground; states

Condensed matter physics has developed a relatively complete theory of common phases in materials leading to many technologically important devices including electronic screens, memory storage, and switching devices. Landau, or mean-field theory, has provided a framework to model, predict, and understand phases and transitions in a surprisingly diverse variety of materials and also dynamical systems. While these conventional ground states have proven technologically important and the underlying theory represents a major success for scientists, these phases have proven incredibly difficult to suppress and often emerge when new materials properties are sought or engineered.To discover novel phases that will lead to a new materials revolution, these common phases need to be suppressed to allow exotic and unconventional properties to emerge. The most common vehicle to turn off conventional phases in materials has been through the introduction of disorder through chemical doping resulting in strong random fields. Many important theories have been formulated and tested to describe the effects of random fields and in particular to account for the fine balance between surface and bulk free energy. However, the use of disorder has proved limiting as properties are often templated into the material and not directly controllable and also the resulting ground state of the material is difficult to understand. Another route, which has more recently been explored in the last decade, to suppress conventional phases is by introducing strong fluctuations. While this can be trivially done with temperature, new phases have emerged by studying quantum systems where the physics are governed by quantum mechanics and the Heisenberg uncertainty principle. The study of quantum systems has resulted in the discovery of many new phases of matter including high temperature superconductors and also quantum spin-liquids where the magnetism is dynamic at any temperature. A limitation of quantum fluctuations is that the properties do not carry over directly to ferroelectric based systems and also multiferroics where magnetic and structural properties are strongly coupled. Also, owing to the strong fluctuating nature of the ground state, the properties have not been found to be easily tunable limiting immediate use for applications. This proposal aims to therefore take a different route by studying classically frustrated systems where a large ground state degeneracy is introduced naturally through the lattice and quantum mechanical effects are small. Emphasis will be placed on lattices based upon a triangular geometry. The lack of strong fluctuations (that exists in quantum systems) provides the ability to controllably tune between different ground states making this route a potential means of creating new switching devices or novel memory storage systems.The proposal aims to investigate classically frustrated magnets and ferroelectrics. These systems can be described within a common framework and will be studied using scattering techniques to provide a bulk real space image of the ground state. The properties will be tuned with magnetic and electric fields supplying a direct route for discovering a new route towards technologically applicable materials. The combined approach of investigating ferroelectrics and magnets will result in a complete understanding applicable to immediate industrial applications. These new materials will lead to the discovery of new phases including new high temperature multiferroics, classical spin liquids, or localized controllable boundaries or defects.

冷凝物质物理学在材料中开发了相对完整的公共阶段理论，导致许多具有技术重要的设备，包括电子屏幕，内存存储和开关设备。兰道（Landau）或均值场理论提供了一个框架，以建模，预测和理解各种材料以及动态系统的各种阶段和过渡。尽管这些传统的基础状态在技术上已被证明是重要的，并且基本理论代表了科学家的重大成功，但这些阶段被证明是难以抑制的难以抑制，并且在寻求新材料的特性或设计新材料时经常出现。要发现新的阶段，这些新阶段将导致新材料革命，需要抑制这些常见阶段，以允许出现和无效的物体来实现Emererge。关闭材料中常规阶段的最常见车辆是通过化学掺杂引入障碍，从而产生强大的随机场。已经制定和测试了许多重要的理论，以描述随机场的影响，尤其是解释了表面和散装自由能之间的良好平衡。但是，由于属性通常被模板模板而不能直接控制，因此疾病的使用已被证明是限制的，而且材料的产生基态也很难理解。在过去的十年中，最近探索了另一条途径，以抑制常规阶段，这是引入强烈的波动。虽然这可以用温度进行动力进行，但通过研究物理学受量子力学和海森伯格不确定性原理控制的量子系统而出现了新的阶段。量子系统的研究导致发现了许多新的物质阶段，包括高温超导体以及在任何温度下磁性动态的量子自旋液体。量子波动的一个局限性是，这些性能不会直接延伸到基于铁电的系统以及磁性和结构特性强烈耦合的多表演系统。同样，由于基态的强烈波动性，尚未发现这些属性很容易调整，可限制对应用的立即使用。因此，该提案旨在通过研究经典沮丧的系统来采取不同的途径，在这些系统中，通过晶格自然引入了大型基态脱落性，量子机械效应很小。重点将基于三角形几何形状放置在晶格上。缺乏强烈的波动（存在于量子系统中）提供了能够在不同的接地状态之间进行控制调整的能力，从而使该路线成为创建新的开关设备或新型内存存储系统的潜在手段。该提案旨在调查经典的磁铁和铁电气。这些系统可以在公共框架中描述，并将使用散射技术研究以提供基态的批量真实空间图像。这些属性将使用磁场和电场调整，该磁场提供直接的途径，以发现通往技术适用材料的新途径。调查铁电和磁铁的合并方法将导致完全理解适用于直接工业应用。这些新材料将导致发现新阶段，包括新的高温多铁，经典旋转液体或局部可控边界或缺陷。

项目成果

Magnetic transitions in the topological magnon insulator Cu(1,3-bdc)

• DOI: 10.1103/physrevb.93.214403
• 发表时间: 2016-06-02
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Chisnell, R.;Helton, J. S.;Lee, Y. S.
• 通讯作者: Lee, Y. S.

Modulated magnetism in PrPtAl

• DOI: 10.1038/nphys3238
• 发表时间: 2015-04-01
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Abdul-Jabbar, Gino;Sokolov, Dmitry A.;Huxley, Andrew D.
• 通讯作者: Huxley, Andrew D.

(C4H12N2)[CoCl4]: tetrahedrally coordinated Co2+ without the orbital degeneracy.

(C4H12N2)[CoCl4]：无轨道简并的四面体配位 Co2。

• DOI: 10.1107/s2052520614024809
• 发表时间: 2015
• 期刊: Acta crystallographica Section B, Structural science, crystal engineering and materials
• 作者: Decaroli C

Comment on "Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations".

评论“由极性纳米区域振动控制的弛豫铁电体的巨型机电耦合”。

• DOI: 10.1126/sciadv.aar5066
• 发表时间: 2019
• 期刊: Science advances
• 影响因子: 13.6
• 作者: Gehring PM

Determination of spin and orbital magnetization in the ferromagnetic superconductor UCoGe

铁磁超导体 UCoGe 中自旋和轨道磁化强度的测定

• DOI: 10.1103/physrevb.92.121107
• 发表时间: 2015
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Butchers M