CAREER: Optical Spectroscopy of the Soft-Modes in Multiferroic Single Crystals

*非技术摘要*新泽西理工学院(NJIT)的这项教师早期职业奖侧重于将多铁性的基础研究与不同水平的学生的教育相结合。多铁性是一类新型的氧化物材料，其磁学和电学性质是相互关联的，在低温下可以相互影响。最近，这些材料在凝聚态和凝聚态以外的领域引起了极大的兴趣，因为多铁性材料在未来的多功能器件中具有广泛的应用潜力，包括磁记录计算机存储器、用于通信的光开关和机械执行器。关于多铁性效应机制的全面理论仍在发展中。拟议的有关原子振动的实验研究将有助于加深对这些效应的理解。这些研究还将有助于寻找新的多铁性，这些多铁性可能会导致未来的设备可以在更弱的磁场和更高的温度下运行。将开发多样化的课程，以促进现代材料研究与教育的融合。NJIT的几门物理课程，例如“光谱学基础”和“高等物理实验室”将与拟议的研究直接相关。将为一年级学生创建一个全面的在线物理入门课程，并将用于当地高中生的外联计划。*技术摘要*新泽西理工学院(NJIT)的这一教师早期职业奖侧重于将多铁性材料中软模的基本光学光谱与不同水平的学生的教育相结合。多铁性磁电材料是一类新型的铁氧体，其磁化强度和极化强度紧密耦合，相互影响。通过施加电场可以改变这些晶体中的磁化强度M，而外加磁场影响极化P。目前还不存在在晶格水平上对P-M耦合的理论理解。拟议的实验将使用国家同步加速器光源的远红外光谱和拉曼散射，两者都在磁场中，以关注这一问题。主要的研究目标是将多铁性单晶的介电函数和磁化强度的反常与软模声子、磁子和晶场红外激发行为之间的相互作用联系起来。与国家同步辐射设施的合作是该项目的关键部分。几门物理课程将与拟议的研究直接相关：研究生的《光谱学基础》和四年级本科生的《高级物理实验室》。将为一年级学生创建一个全面的物理入门在线课程以及一个基于网络的互动工具“为即将到来的测验做准备”，并将用于针对当地高中生的外联方案。

*****NON-TECHNICAL ABSTRACT*****This Faculty Early Career Award at New Jersey Institute of Technology (NJIT) focuses on integrating fundamental studies of multiferroics with the education of students at different levels. Multiferroics belong to a novel class of oxide materials, whose magnetic and electrical properties are interconnected and can influence each other at low temperatures. Recently these materials have attracted great interest within the condensed-matter community and beyond due to the recognized potentials of multiferroics for future multifunctional device applications including magnetically recorded computer memory, optical switches for communication, and mechanical actuators. A comprehensive theory of the mechanisms for multiferroic effects is still under development. The proposed experimental studies of the related atomic vibrations will contribute to an increased understanding of these effects. The studies will also help in the search for new multiferroics that may lead to future devices that can operate in weaker magnetic fields and at higher temperatures. A diverse curriculum will be developed to promote the integration of modern materials research and education. Several Physics courses at NJIT, e.g. "Fundamental of Spectroscopy" and "Advanced Physics Laboratory", are to be directly associated with the proposed research. A comprehensive online course of Introductory Physics will be created for freshman students and will be used in outreach programs to local high-school students.*****TECHNICAL ABSTRACT*****This Faculty Early Career Award at New Jersey Institute of Technology (NJIT) focuses on the integration of fundamental optical spectroscopy of the soft modes in multiferroic materials with education of students at different levels. Multiferroic magnetoelectrics belong to a novel class of ferroic oxides, whose magnetization and electrical polarization are closely coupled and can influence each other. By applying an electric field one can change the magnetization M in these crystals, while an external magnetic field affects the polarization P. A theoretical understanding of the P-M coupling at the crystal lattice level does not currently exist. The proposed experiments will use far-infrared spectroscopy at the National Synchrotron Light Source and Raman scattering, both in a magnetic field, to focus on this issue. The major research goal is to relate the interplay between anomalies in the dielectric function and magnetization of multiferroic single crystals to the behavior of the soft mode phonons, magnons, and crystal-field infrared-active excitations. Collaboration with National synchrotron radiation facilities is a key part of this project. Several Physics courses will be directly associated with the proposed research: "Fundamental of Spectroscopy" for graduate students and "Advanced Physics Laboratory" for fourth-year undergraduates. A comprehensive online course of Introductory Physics as well as a web-based interactive tool "Prepare for the Coming Quiz" will be created for freshman students and will be used in outreach programs to local high-school students.