Investigation of frustrated antiferromagnetic compounds using ultrasonic velocity measurements

使用超声波速度测量研究受挫反铁磁化合物

• 批准号: RGPIN-2018-04889
• 负责人: Quirion, Guy
• 金额: $ 1.82万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=662815
• 关键词: Investigation; frustrated; antiferromagnetic; compounds; using

Triangular lattice and pyrochlore antiferromagnets are perfect prototype of 2D and 3D frustrated spin systems where two magnetic moments cannot be anti-parallel to each other owing to constraints imposed by the lattice geometry. Due to the magnetic frustration, which leads to a large number of degenerate spin configurations, the fundamental properties of these materials are still not fully understood. As a result, according to simple nearest neighbor interaction classical models, spins on the pyrochlore lattice are not expected to develop any kind of long range order down to 0 K. In general, the physical properties of these systems are rather associated with antisymmetric exchange interaction (Dzyaloshinskii-Moriya), dipolar interaction, anisotropy, magnetoelastic couplings, and even quantum effects at low temperatures. Consequently, these frustrated systems display many new exotic states such as: new non-collinear orders, spin liquids, spin glasses, spin ices, and quantum spin ices.******The proposed research program also focuses on the study of multiferroic magnetic materials, which are compounds that simultaneously show antiferromagnetic, ferroelectric, and ferroelastic properties. Besides the fundamental scientific interest, we are principally interested in multiferroic compounds which show a strong interplay between magnetism and ferroelectricity. This coupling, referred to as the magnetoelectric effect, can potentially be used as an alternative means for controlling the magnetization in future electronic memory devices, actuators, switches, and magnetic field sensors. A renewed interest in this field has been triggered by recent results which show that a subset of frustrated magnets, which favor non-collinear spin configuration (triangular lattice antiferomagnets), are potentially good candidates for the observation of strong magnetoelectric effects.******The fundamental elastic properties of this class of materials are accessed using high resolution ultrasonic velocity measurements. Our laboratory offers a flexible way to investigate the elastic properties of single crystals under hydraulic pressure as a function of temperature and magnetic field. We are one of the few groups in the world capable of measuring elastic properties and magnetic phase diagrams as a function of three external parameters over a wide range (50 mK - 300 K, 0 - 18 Tesla, and 0 - 15 kbar). Our approach holds potential for the acquisition of significant results in order to clarify the nature of the coupling between elastic, electric, and magnetic properties observed in this family of compounds. These results will also provide guidance for theoretical models developed by our group. This work should therefore contribute to a better understanding of the properties of frustrated antiferromagnets and could lead to the development of new materials for technological applications.*****

三角晶格和烧绿石反铁磁体是二维和三维阻挫自旋系统的完美原型，其中两个磁矩由于晶格几何形状的约束而不能彼此反平行。由于磁阻挫，导致大量的简并自旋配置，这些材料的基本性质仍然没有完全理解。 因此，根据简单的最近邻相互作用经典模型，烧绿石晶格上的自旋预计不会发展任何种类的长程有序到0 K。一般来说，这些系统的物理性质与反对称交换相互作用（Dzyaloshinskiii-Moriya），偶极相互作用，各向异性，磁弹性耦合，甚至低温下的量子效应有关。 因此，这些受抑系统显示出许多新的奇异状态，如：新的非共线秩序，自旋液体，自旋玻璃，自旋冰和量子自旋冰。拟议的研究计划还侧重于多铁性磁性材料的研究，这些材料是同时显示反铁磁，铁电和铁弹特性的化合物。 除了基本的科学兴趣，我们主要对磁性和铁电性之间表现出强烈相互作用的多铁性化合物感兴趣。这种耦合称为磁电效应，可以潜在地用作用于控制未来电子存储器设备、致动器、开关和磁场传感器中的磁化的替代手段。 最近的研究结果表明，一个有利于非共线自旋构型（三角晶格反铁磁体）的受抑磁体子集是观察强磁电效应的潜在良好候选者。这类材料的基本弹性性能的访问使用高分辨率的超声波速度测量。我们的实验室提供了一种灵活的方法来研究单晶在液压下的弹性特性，作为温度和磁场的函数。我们是世界上少数几个能够测量弹性性能和磁相图的团队之一，这些性能和磁相图是三个外部参数在宽范围内（50 mK - 300 K，0 - 18 Tesla和0 - 15 kbar）的函数。我们的方法具有潜在的收购显着的结果，以澄清在这个家庭的化合物中观察到的弹性，电，磁性能之间的耦合的性质。这些结果也将为我们小组开发的理论模型提供指导。因此，这项工作应该有助于更好地理解受抑反铁磁体的性质，并可能导致新材料的技术应用的发展。