应力敏感型锰氧化物薄膜的生长和性能研究

The growth of manganite thin films and substrate-induced strain effect is critical for their application in functional devices and the understanding of underlying physics. The half-doped manganites such as Pr0.5Sr0.5MnO3(PSMO) show a ground state locating at phase boundary between the ferromagnetic metal and antiferromagnetic insulator where the two phases compete with each other strongly. Such strong phase competition yields that the electric and magnetic properties of the films are greatly sensitive to the external perturbs such as temperature, strain, electric current and magnetic field. A distinguish strain effect is expected in this kind of films may. In this project, we plan to focus on PSMO and the related doped films. The influence of film growth, substrate-induced strain and film thickness on the electric and magnetic diagram will been comprehensively studied. By using the heterostructure of mangnite/ferroelectrics in which the substrate-induced strain could be in-situ modified, the strain effect on the electric current-induced electroresistance and magnetoresistance will also be investigated. These studies would benefit for the application of the manganite films and understanding of the physics of the materials.

锰氧化物薄膜的生长和应力效应研究对锰氧化物作为功能材料的应用和物理机制的认识都很重要。Pr0.5Sr0.5MnO3(PSMO)等半掺杂锰氧化物的基态在相图上位于铁磁金属相和反铁磁绝缘相两相的交界处，内部存在两相之间的激烈竞争。这种激烈的相竞争使得材料对外界干扰反应强烈，比一般的锰氧化物显示出更大的应力敏感性。本项目将以PSMO及其掺杂系列应力敏感型的锰氧化物薄膜为研究对象，在各种衬底上制备不同厚度薄膜，系统研究制备工艺对薄膜晶相生长和界面应力的控制；在钙钛矿结构铁电衬底上外延生长锰氧化物薄膜形成异质结构，利用这种结构可以实现应力原位调制的优越性，探究应力对薄膜电磁相图、磁致电阻和电致电阻效应的调制。本项目的研究目标是阐明薄膜生长和界面应力对材料性能的作用和增大电致电阻、磁致电阻以及弹性电阻等效应的途径，以提高相关功能器件的性能。

Pr0.5Sr0.5MnO3(PSMO)等半掺杂锰氧化物的基态在相图上位于铁磁金属相和反铁磁绝缘相两相的交界处，内部存在两相之间的激烈竞争。这种激烈的相竞争使得材料对外界干扰反应强烈，比一般的锰氧化物显示出更大的应力敏感性，呈现出可能的应用前景。应力敏感型锰氧化物薄膜的生长和性能研究这一项目主要研究了PSMO等薄膜等的制备工艺，包括衬底取向、晶格失配度、生长温度、氧含量、膜厚和后退火处理等对薄膜结构、相图、电致电阻(ER)和磁致电阻(MR)效应等电磁性能的影响，由此我们了解了薄膜的生长规律，揭示了晶格失配度、薄膜外延取向和厚度等生长参数和物理性质的关联，生长出了高品质的外延薄膜；在PMN-PT衬底上外延生长锰氧化物薄膜构成的异质结构，通过衬底的压电效应，研究了应力的原位变化对物性的调制，撇清了其他因素的干扰，阐明应力对ER、MR效应的作用机制和获得巨大ER、MR效应的途径，为开发高性能磁、电敏感材料和器件提供依据。通过本项目的实施，我们已发表论文3篇，另有2篇正在投稿当中，培养和协助培养研究生3名。