Electric Field Effects on the Ferromagnetism of Dynamically Phase Separated Manganites

电场对动态相分离锰矿铁磁性的影响

• 批准号: 1410237
• 负责人: Amlan Biswas
• 金额: $ 37.6万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-15 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1410237&HistoricalAwards=false
• 关键词: Electric; Field; Effects; Ferromagnetism; Dynamically

Non-technical AbstractThis award from the Division of Materials Research supports the University of Florida with a project to study the effect of electric fields on the magnetism in a class of materials called manganites. Manganites can exist in various magnetic phases known as ferromagnetic, antiferromagnetic, and paramagnetic and can even form a phase separated state in which these magnetic phases coexist. The principal investigator and his research team of graduate and undergraduate students grow crystalline thin films of manganites and control their phase separated state to form nanometer to micrometer sized ferromagnetic regions embedded in an antiferromagnetic insulating matrix. The samples are then subjected to external stress and electric field and the effect on the ferromagnetic regions is measured using techniques such as microscopy and neutron reflectometry. A possible outcome of this project is the control of the magnetism in using an electric field, which could lead to data storage devices with reduced energy consumption. Since this project includes both sample preparation and measurement, young scientists are trained to use a broad array of modern experimental techniques and the expertise acquired enhances their future career options in both the industry and academe.Technical AbstractPerovskite manganese oxides (manganites) exhibit competing phases with different electronic, magnetic, and structural properties which can result in phase coexistence. In high-quality thin films of manganites the coexistent phases have shown evidence that they behave in a dynamic and fluid-like manner and can even move spatially within the solid sample under the influence of strain and electric field. This project investigates this fluid-like behavior in manganites and its possible application to control the magnetic properties of the material with an electric field. The experiments are designed to: (1) ascertain the physical mechanism behind the fluid-like behavior of the ferromagnetic regions in the dynamic phase coexistence state and hence, find the optimal conditions for producing such a state, (2) investigate the effects of electric field, strain, and sample geometry on the dynamic phase separated state, and (3) measure the effect of an electric field on the magnetic properties. The high-quality thin films of manganites are grown using pulsed laser deposition. The local and bulk properties of the thin films and fabricated micro/nanostructures are then studied using techniques such as low temperature conducting atomic force microscopy, spin-polarized neutron reflectometry, resistivity, and magnetization measurements. Density functional theory calculations are used to model the experimental results and suggest new directions for the experimental efforts. The results of this project are expected to reveal a novel method for generating an electric field effect on the magnetic properties of a material. Since this project includes both sample preparation and measurement, young scientists are trained to use a broad array of modern experimental techniques and the expertise acquired enhances their future career options in both the industry and academe.

非技术摘要该奖项由材料研究部颁发，支持佛罗里达大学的一个项目，研究电场对一类称为锰氧化物的材料的磁性的影响。锰氧化物可以以各种磁性相存在，称为铁磁性、反铁磁性和顺磁性，甚至可以形成这些磁性相共存的相分离状态。首席研究员和他的研究生和本科生团队生长锰氧化物晶体薄膜，并控制其相分离状态，以形成嵌入反铁磁绝缘基质中的纳米至微米尺寸的铁磁区域。然后将样品置于外部应力和电场中，并使用显微镜和中子反射计等技术测量对铁磁区域的影响。该项目的一个可能成果是使用电场控制磁性，这可能导致数据存储设备的能耗降低。由于该项目包括样品制备和测量，年轻的科学家接受培训，使用广泛的现代实验技术和获得的专业知识，提高了他们未来的职业选择，在工业界和工业界。技术摘要锰氧化物（锰氧化物）具有不同的电子，磁性和结构性能，可以导致相共存的竞争相。在高质量的锰氧化物薄膜中，共存的相已经显示出它们以动态和流体状的方式行为的证据，甚至可以在应变和电场的影响下在固体样品内空间移动。该项目研究了锰氧化物中的这种类似流体的行为，以及它在用电场控制材料磁特性方面的可能应用。这些实验的目的是：（1）确定铁磁区域在动态相共存状态下的流体行为背后的物理机制，并因此找到产生这种状态的最佳条件，（2）研究电场，应变和样品几何形状对动态相分离状态的影响，以及（3）测量电场对磁性能的影响。采用脉冲激光沉积法制备了高质量的锰氧化物薄膜。然后，使用诸如低温传导原子力显微镜、自旋极化中子反射计、电阻率和磁化测量等技术研究薄膜和制造的微/纳米结构的局部和本体性质。密度泛函理论计算被用来模拟实验结果，并为实验工作提出新的方向。该项目的结果有望揭示一种新的方法，用于产生对材料磁性能的电场效应。由于该项目包括样品制备和测量，年轻的科学家接受培训，使用广泛的现代实验技术，所获得的专业知识增强了他们未来在行业和企业中的职业选择。