Terahertz spectroscopy of collective excitations in ordered phases of overdoped manganites

过掺杂锰氧化物有序相集体激发的太赫兹光谱

• 批准号: 190269856
• 负责人: Professor Dr. Martin Dressel
• 金额: --
• 依托单位: I. Physikalisches Institut - Festkörper- und Tieftemperaturphysik -
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/190269856?language=en
• 关键词: Terahertz; spectroscopy; collective; excitations; ordered

In perovskite oxide manganites R1-xAxMnO3 (R – rare earth, A – alkaline element) the fineinterplay of nearly equal-strength spin, charge, lattice, and orbital interactions leads to a varietyof electronically correlated ground states. It provides the possibility to tune them by moderatevariations of system parameters, such as temperature, composition, particle size, internal strain,magnetic field, etc., which has attracted a lot of attention during past decades. However, theorigin of the ground states and the mechanisms of the correspondent phase transitions are notcompletely resolved. Presently, clarification of physical models of charge, orbital, and magneticorders in the systems is of broader interest in the context of electronically correlated transitionmetal oxides, in particular of the overdoped regime, x > 0.5, a sector of the phase diagram that isless explored compared to the underdoped one, where colossal magnetoresistance is observed.We plan to study the microscopic origin and collective modes of various charge, magneticallyand orbitally ordered phases of the family R1-xAxMnO3 (0.5≤x≤1) by investigating the nano-sizeeffects on magnetic and charge order, and thin-film, A-site cation ordering and strain effects onthe electronic transitions, the energy gaps and the phonon modes using optical spectroscopy withthe focus on low energies, of few millielectronvolts and below, where collective electroniceffects in solids are expected to show up. A set of spectrometers will be employed, includingoptical ellipsometer, infrared Fourier-transform spectrometer and terahertz and microwavesetups for low energies, complemented with magnetic measurements. A series of bulk (polycrystalline)and thin-film (epitaxially grown) compounds R1-xAxMnO3 (R = La, Pr, A = Ca) willbe studied with 0.5 < x < 1, respectively.

在钙钛矿氧化物锰酸盐 R1-xAxMnO3（R - 稀土元素，A - 碱性元素）中，几乎相等强度的自旋、电荷、晶格和轨道相互作用的精细相互作用导致了各种电子相关基态的调节。通过适度改变系统参数，如温度、成分、颗粒尺寸、内应变、磁场等，这在过去的几十年里引起了很多关注。目前，基态的起源和相应相变的机制尚未完全解决，在电子相关的过渡金属氧化物的背景下，系统中电荷、轨道和磁序的物理模型的澄清引起了更广泛的兴趣。特别是过掺杂状态，x > 0.5，与未掺杂状态相比，相图的这一部分很少被探索，其中观察到巨大的磁阻。我们计划研究微观起源和通过研究纳米尺寸对磁性和电荷有序性的影响，以及薄膜、A 位阳离子有序性和应变效应，研究 R1-xAxMnO3 (0.5≤x≤1) 族的各种电荷、磁性和轨道有序相的集体模式使用光学光谱法研究电子跃迁、能隙和声子模式，重点关注几毫电子伏及以下的低能量，其中固体中的集体电子效应预计会出现。将使用多种光谱仪，包括光学椭偏仪、红外傅里叶变换光谱仪以及低能量太赫兹和微波装置，并辅以一系列块体（多晶）和薄膜（外延生长）化合物 R1-xAxMnO3 (R = La 、Pr、A = Ca) 将分别以 0.5 < x < 1 进行研究。

项目成果

Terahertz–infrared electrodynamics of overdoped manganites La1–xCaxMnO3

过掺杂锰氧化物 La1âxCaxMnO3 的太赫兹红外电动力学

• DOI: 10.1080/01411594.2014.953508
• 发表时间: 2014
• 期刊: Phase Transitions
• 影响因子: 1.6
• 作者: L. S.Kadyrov;B. Gorshunov;E.Zhukova;V. I.Torgashev;A.S.Prokhorov;E.A. Motovilova;F. Fischgrabe;V.Moshnyaga;T.Zhang;R.Kremer;U. Pracht;S. Zapf;J. Pokorný;G. Untereiner;S. Kamba;M.Dressel
• 通讯作者: M.Dressel

Terahertz-infrared spectroscopy of overdoped manganites La1−xCaxMnO3

• DOI: 10.1016/j.physb.2014.11.070
• 发表时间: 2015-03
• 期刊: Physica B-condensed Matter
• 影响因子: 2.8
• 作者: L. Kadyrov;E. Zhukova;V. Torgashev;B. Gorshunov;A. Prokhorov;E. Motovilova;F. Fischgrabe;V. Moshnyaga;Tao Zhang;R. Kremer;U. Pracht;S. Zapf;J. Pokorny;G. Untereiner;S. Kamba;M. Dressel

Boson peak in manganites

锰酸盐中的玻色子峰

• DOI: 10.1088/1742-6596/486/1/012001
• 发表时间: 2014
• 期刊: Journal of Physics: Conference Series
• 作者: B.P.Gorshunov;E.S.Zhukova;V.I.Torgashev;L.S. Kadyrov;E.A.Motovilova;F. Fischgrabe;V.Moshnyaga;T.Zhang;R.Kremer;U.Pracht;S.Zapf;M.Dressel
• 通讯作者: M.Dressel