Exotic Quantum Responses in Complex Oxide Thin Films

复合氧化物薄膜中的奇异量子响应

• 批准号: 1905861
• 负责人: Jon-Paul Maria
• 金额: $ 35.44万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1905861&HistoricalAwards=false
• 关键词: Exotic; Quantum; Responses; Complex; Oxide

Nontechnical description. The project explores the intrinsic electronic and optical properties in strongly correlated electron systems. Unlike in semiconductors, which are currently utilized in information technology, electrons in these material systems are strongly coupled and collectively respond to external stimuli, thus offering responses that are beyond conventional semiconductor materials. Enabled by the improvement to synthesize vanadate and titanate thin films with exceptionally low defect concentration by hybrid molecular beam epitaxy the electronic properties of these ultrapure materials are explored. Growth experiments are performed to synthesize films of the newly proposed insulator BiVO3 and ultimately the quaternary compound Bi1-xSrxVO3. The goal is to demonstrate that electric field control over electronic properties can be realized in these materials. The doping of the strained thin films is explored to experimentally confirm that the superconducting transition temperature can be induced and enhanced by utilizing epitaxial strain. The research is expected to have significant scientific and technological impact, by providing fundamentally new insights into electronic phase transition materials that can be used in sensors, logic devices for high performance power efficient computing, and quantum computation. The program provides multidisciplinary training opportunities to graduate and undergraduate students in the area of thin film synthesis and characterization of electronic phase transition materials. Outreach activities target K-12 audiences to nurture their curiosity in science and technology.Technical description. The project focuses on fundamental studies of growth kinetics relevant to the synthesis of complex oxide thin films with perovskite structure. Growth experiments aim to map conditions to access a self-regulated growth mode for the ternary oxide compounds BiVO3 using a combinatorial growth approach, i.e. conventional molecular beam epitaxy and chemical beam epitaxy. A growth strategy is developed for the self-regulated growth of BiVO3, which enables the thin film synthesis of the quaternary compound Bi1-xSrxVO3. A collaborative research approach is taken to analyze the quaternary system using angle resolved photoemission spectroscopy, transmission electron microscopy, scanning tunneling microscopy, and temperature dependent magnetotransport and nonlinear optical spectroscopy. The in-depth analysis of electronic and optical properties of the solid solution Bi1-xSrxVO3 opens up an entirely new design space in the strongly correlated vanadate material system, in which electric field control over electronic properties near the quantum critical point of the band-filled metal-to-insulator transition is inherently built-in. Detailed donor doping studies of the strained quantum paraelectric SrTiO3 and CaTiO3 are conducted to explore whether a superconducting phase can be induced in CaTiO3, and if the superconducting transition temperatures in SrTiO3 can be enhanced if the quantum critical behavior is stabilized at higher temperature using epitaxial strain. The overarching goal of the project is to explore new quantum phases in complex oxides exhibiting strong electron correlation effects and to understand their exotic responses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述。该项目探索强相关电子系统中固有的电子和光学特性。与目前信息技术中使用的半导体不同，这些材料系统中的电子是强耦合的，并且共同响应外部刺激，从而提供超越传统半导体材料的响应。通过混合分子束外延改进合成具有极低缺陷浓度的钒酸盐和钛酸盐薄膜，探索了这些超纯材料的电子特性。进行生长实验以合成新提出的绝缘体 BiVO3 薄膜，并最终合成四元化合物 Bi1-xSrxVO3。目标是证明可以在这些材料中实现对电子特性的电场控制。对应变薄膜的掺杂进行了探索，以通过实验证实利用外延应变可以诱导和提高超导转变温度。该研究预计将产生重大的科学和技术影响，为可用于传感器、高性能节能计算和量子计算的逻辑器件的电子相变材料提供全新的见解。该计划为研究生和本科生提供薄膜合成和电子相变材料表征领域的多学科培训机会。外展活动针对 K-12 受众，培养他们对科学技术的好奇心。技术描述。该项目的重点是与钙钛矿结构复合氧化物薄膜合成相关的生长动力学的基础研究。生长实验旨在利用组合生长方法（即传统分子束外延和化学束外延）绘制三元氧化物 BiVO3 的自我调节生长模式的条件。开发了 BiVO3 自我调节生长的生长策略，从而实现了四元化合物 Bi1-xSrxVO3 的薄膜合成。采用协作研究方法，使用角分辨光电子能谱、透射电子显微镜、扫描隧道显微镜、温度依赖性磁输运和非线性光学光谱来分析四元系统。对固溶体 Bi1-xSrxVO3 电子和光学性质的深入分析，在强相关钒酸盐材料体系中开辟了全新的设计空间，其中电场控制带填充的量子临界点附近的电子性质金属到绝缘体的转变本质上是内置的。对应变量子顺电 SrTiO3 和 CaTiO3 进行了详细的施主掺杂研究，以探讨是否可以在 CaTiO3 中诱导超导相，以及如果使用外延应变在较高温度下稳定量子临界行为，是否可以提高 SrTiO3 中的超导转变温度。该项目的总体目标是探索复合氧化物中表现出强电子关联效应的新量子相，并了解它们的奇异反应。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的影响进行评估，被认为值得支持审查标准。

项目成果

Self-regulated growth of [111]-oriented perovskite oxide films using hybrid molecular beam epitaxy

• DOI: 10.1063/5.0040047
• 发表时间: 2021-02
• 期刊: APL Materials
• 影响因子: 6.1
• 作者: J. Roth;T. Kuznetsova;L. Miao;A. Pogrebnyakov;N. Alem;R. Engel-Herbert

Growth of SrMoO3 thin films by suboxide molecular beam epitaxy

低氧化物分子束外延生长 SrMoO3 薄膜

• DOI: 10.1116/6.0002853
• 发表时间: 2023
• 期刊: Journal of Vacuum Science & Technology A
• 影响因子: 2.9
• 作者: Kuznetsova, Tatiana;Roth, Joseph;Lapano, Jason;Pogrebnyakov, Alexej;Engel-Herbert, Roman
• 通讯作者: Engel-Herbert, Roman

Toward ultraclean correlated metal CaVO3

迈向超净相关金属CaVO3

• DOI: 10.1063/5.0143611
• 发表时间: 2023
• 期刊: APL Materials
• 影响因子: 6.1
• 作者: Kuznetsova, Tatiana;Müller, Mahni;Fischer, Saskia F.;Engel-Herbert, Roman
• 通讯作者: Engel-Herbert, Roman