EAGER: Tuning Orbital Order in Nickelate Superlattices with Atomic Layer-by-Layer Growth using Laser Molecular Beam Epitaxy (MBE)

非技术描述：自1986年发现层状铜氧化物高温超导性以来，其机理一直是研究的热点。最近，理论上预测高温超导铜氧化物中的电子结构可以在镍酸镧中实现，当镍酸镧被夹在绝缘氧化物如铝酸镧之间时，在所谓的超晶格中。镍酸镧和铝酸镧层都需要非常薄，仅两个原子层。证明或反驳这一预测不仅有助于理解高温超导的机制，而且可能导致在铜酸盐，镍酸盐和其他材料系统中发现新的高温超导体。本计画的目标是利用雷射分子束磊晶技术，以原子层接层的方式成长出镍酸盐超晶格，并量测其电子结构特性与超导电性，以验证理论预测。该项目的成功可以显着推进强相关的过渡金属氧化物，设计材料和氧化物异质结构的纳米级工程领域的知识。该项目资助一名女研究生攻读博士学位。因此，直接扩大了代表性不足群体的参与。技术规格：这项EAGER资助的重点是利用激光分子束外延技术通过原子逐层生长来调谐镍酸盐超晶格中的轨道顺序。最近，理论上已经预测，使用降维和外延应变，可以在镍酸镧中实现高Tc超导铜酸盐中的电子结构，通过将其夹在绝缘氧化物如铝酸镧的超晶格中，其中每个周期包含每种材料的一个单胞。掺杂可以诱导超导性。没有实验证据已被报道，尽管许多努力和理论预测的有效性受到质疑。本计画利用一种新的薄膜沉积技术，即从分离的氧化物靶材进行雷射分子束磊晶，来达成镍酸盐超晶格的原子层接层成长。这种方法是更适当的比生长技术，已尝试在调整的轨道秩序和诱导的镍酸盐超晶格的超导性。该项目的成功可以显着推进强相关的过渡金属氧化物，材料设计和氧化物异质结构的纳米级工程领域的知识。该项目为一名女研究生提供多学科培训，直接扩大了代表性不足群体的参与。

NON-TECHNICAL DESCRIPTION: The mechanism that leads to the high temperature superconductivity in a family of layered copper oxides has been an active area of research since its discovery in 1986. Recently, it has been predicted theoretically that the electronic structure in the high temperature superconducting cuprates can be realized in lanthanum nickelate when it is sandwiched between insulating oxide such as lanthanum aluminate in the so-called superlattices. Both the lanthanum nickelate and lanthanum aluminate layers need to be very thin, just two atomic layers. Proving or disproving this prediction can not only help understand the mechanism of high temperature superconductivity, but potentially lead to discovery of new high temperature superconductors in cuprates, nickelates, and other material systems. The goal of this project is to fabricate the nickelate superlattices by atomic layer-by-layer growth using laser molecular beam epitaxy and measure their electronic structure properties and superconductivity to test the theoretical prediction. Success of the project can significantly advance the knowledge in the areas of strongly correlated transition metal oxides, materials by design, and nanoscale engineering of oxide heterostructures. The project supports a female graduate student for her Ph.D. degree, thus directly broadens the participation of underrepresented groups. TECHNICAL DETAILS: This EAGER grant focuses on tuning orbital order in nickelate superlattices by atomic layer-by-layer growth using laser molecular beam epitaxy. Recently, it has been predicted theoretically that using reduced dimensionality and epitaxial strain the electronic structure in the high-Tc superconducting cuprates can be realized in lanthanum nickelate by sandwiching it between insulating oxide such as lanthanum aluminate in superlattices where each period contains one unit cell of each materials. Doping could then induce superconductivity. No experimental proof has been reported despite numerous efforts and the validity of the theoretical prediction has been questioned. This project uses a new film deposition technique, laser molecular beam epitaxy from separate oxide targets, to achieve the atomic layer-by-layer growth of the nickelate superlattices. This approach is more appropriate than the growth techniques that have been attempted in tuning the orbital order and inducing superconductivity in the nickelate superlattices. The success of the project can significantly advance the knowledge in the areas of strongly correlated transition metal oxides, materials design, and nanoscale engineering of oxide heterostructures. The project provides multidisciplinary training for a female graduate student, directly broadening the participation of an underrepresented group.