Physics of rare earth - transition metal permanent magnets: theory of their magnetostriction

稀土物理-过渡金属永磁体：磁致伸缩理论

• 批准号: 1765002
• 金额: --
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1765002
• 关键词: Physics; rare; earth; transition; metal

Permanent magnets are pervasive in both established and developing technologies. Found in motors and generators, transducers, magnetomechanical devices and magnetic field and imaging systems, there is a multi-billion pound worldwide market for them. They are also both fascinating and challenging in terms of their fundamental materials physics. At the Universities of Warwick and Birmingham an integrated EPSRC-funded theory-experiment programme - the PRETAMAG project (Investigations of the Physics underlying the principles of design of Rare Earth Transition metAl permanent MAGnets) - is uncovering key design principles. This PhD project is part of this effort and will be directed at developing the theory for important magneto-structural and magnetoelastic effects. The project will involve condensed matter physics theory and high performance computing.Most strong magnets are comprised of rare earth (RE) and transition metal (TM) atoms arranged in specific crystal structures. The TM element, such as iron or cobalt, helps the ferromagnetism to persist to high temperatures and the RE component, such as samarium or neodymium, is there to generate a large magnetisation which is hard to reorientate away from an easy' direction specified by the crystal structure. There is now a concerted effort worldwide to come up with new permanent magnetic materials with improved magnetic characteristics and reduced dependence on critical elements. Each RE atom in the magnet has a magnetic moment which is set up by its nearly localised f-electrons. These moments are immersed in a glue of septillions of valence electrons coming from all the RE and TM atoms. Local magnetic moments associated with the TM atoms can also emerge from this complex electron fluid. We will establish and apply a theory (see 1) which provides a parameter-free accurate account of this physics and enables predictive modelling of the temperature, compositional and structural dependence of the magnetic hardness of the RE-TM magnets. At each stage, we will test and improve the theory by comparison with detailed experimental measurements.

永磁体在现有和发展中的技术中都很普遍。用于电机和发电机、换能器、磁机械设备、磁场和成像系统，它们在全球有数十亿英镑的市场。在基础材料物理学方面，它们既迷人又具有挑战性。在华威大学和伯明翰大学，epsrc资助的一个综合理论实验项目——PRETAMAG项目（稀土过渡金属永磁体设计原理的物理学基础研究）——正在揭示关键的设计原理。这个博士项目是这一努力的一部分，将致力于发展重要的磁结构和磁弹性效应的理论。该项目将涉及凝聚态物理理论和高性能计算。大多数强磁体由稀土（RE）和过渡金属（TM）原子组成，排列成特定的晶体结构。TM元素，如铁或钴，有助于铁磁性在高温下保持不变，而RE元素，如钐或钕，则产生很大的磁化，很难从晶体结构指定的简单方向重新定向。现在，全世界都在共同努力，开发新的永磁材料，提高磁性，减少对关键元素的依赖。磁体中的每个稀土原子都有一个磁矩，这个磁矩是由它的近局域化的f电子建立的。这些瞬间沉浸在来自所有稀土原子和TM原子的数以千万计的价电子的粘合剂中。与TM原子相关的局部磁矩也可以从这种复杂的电子流体中产生。我们将建立并应用一个理论（见1），该理论提供了该物理的无参数准确描述，并能够对RE-TM磁体的磁硬度的温度、成分和结构依赖性进行预测建模。在每个阶段，我们将通过与详细的实验测量相比较来测试和改进理论。