Theory and Simulation of Ferroic Materials

材料中的对称性破缺常常产生突现的物理行为。常见的例子包括（铁）磁中的时间反转对称破缺和铁电中的空间反转对称破缺，但也存在大量其他类型的对称破缺。ABX3钙钛矿有时被用作这方面的原型示例材料，因为它们可以经历各种类型的电子，原子和自旋排序，以不同的方式打破对称性并诱导新类型的特性，通常具有技术应用的潜力。该项目将使用各种计算和理论工具研究这些类型的材料，包括密度泛函理论（DFT）。反铁电体（AFE）：由于其双磁滞回线的形状，AFE具有储能潜力，但它们相对罕见且研究不足。该项目旨在为具有增强性能的新型AFE的设计提供新的基本观点。铁性的动力学和激发：该项目将从DFT建立基于原子势的“第二原理”，以研究铁性中的相变，热性质（如负热膨胀）和拓扑对象（例如畴壁，涡旋和skyrmions）。- 复合氧化物界面：材料之间或内部的界面可以诱导在体中未观察到的涌现现象，例如2DEG，隐藏的磁序，多铁性行为，交换偏置的电场反转，仅举几例。奇特的铁电体：典型的（真正的）铁电体拥有广泛的潜在应用。该项目旨在揭示新的非典型类型，如弛豫，非正常，触发和超铁电体，它们可以显示出与未来新技术潜在相关的不寻常特性。

Symmetry breaking in materials often produces emergent physical behaviour. Common examples include time-reversal symmetry breaking in (ferro)magnetics and spatial-inversion symmetry breaking in ferroelectrics, but there exists a plethora of other types. ABX3 perovskites are sometimes used as a prototypical example material in this regard, since they can undergo various types of electronic, atomic and spin orderings that break symmetry in different ways and induce new types of properties, often with potential for technological applications. This project will study these types of materials using a variety of computational and theoretical tools, including density functional theory (DFT). Several projects are available within this theme, including:- Anti-ferroelectrics (AFEs): Due to the shape of their double hysteresis loop, AFEs have potential for energy storage but they are relatively rare and understudied. This project aims to provide new fundamental perspectives towards the design of new AFEs with enhanced properties.- Dynamics and excitations of ferroics: This project will build "second principles" based atomic potentials, from DFT, in order to study phase transitions, thermal properties (such as negative thermal expansion), and topological objects (e.g. domain walls, vortices and skyrmions) in ferroics. - Complex oxide interfaces: Interfaces between or within materials can induce emergent phenomena not observed in the bulk, such as 2DEGs, hidden magnetic order, multiferroic behaviour, electric-field reversal of exchange bias, to name a few.- Exotic ferroelectrics: Typical (proper) ferroelectrics host a wide range of potential applications. This project aims to reveal new atypical types, such as relaxor, improper, triggered and hyper- ferroelectrics, which can display unusual properties potentially relevant for novel future technologies