极性补偿对LaMnO_(3)/LaNiO_(3)超晶格交换偏置场强度的影响  

Influence of polarity compensation on exchange bias field in LaMnO_(3)/LaNiO_(3) superlattices

作　　者：魏浩铭 张颖 张宙 吴仰晴 曹丙强[2] Wei Hao-Ming;Zhang Ying;Zhang Zhou;Wu Yang-Qing;Cao Bing-Qiang(School of Physics and Physical Engineering,Qufu Normal University,Qufu 273165,China;School of Material Science and Engineering,University of Jinan,Jinan 250022,China)

机构地区：[1]曲阜师范大学物理工程学院,曲阜273165 [2]济南大学材料科学与工程学院,济南250022

出　　处：《物理学报》2022年第15期223-228,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11904198,51902179,51872161)资助的课题。

摘　　要：钙钛矿超晶格中蕴含着丰富的磁现象,特别是锰酸镧/镍酸镧超晶格中的异常磁交换偏置现象是一个研究热点.本文采用脉冲激光沉积技术,制备出不同取向的锰酸镧/镍酸镧超晶格,并对超晶格的电输运性能和交换偏置现象进行了系统的研究.实验发现,超晶格在不同取向的衬底上外延生长并保持晶格应力;超晶格的母体是Mott绝缘体并遵循二维Mott变程跃迁导电机理;不同取向的超晶格都表现出交换偏置现象;场冷和零场冷曲线表明在低温下超晶格中存在两种不同的磁性组元.对超晶格交换场强度的进一步分析发现,交换场强度与超晶格的取向以及超晶格与衬底界面处的极性补偿有关.在不同温度下都观察到,极性连续的超晶格的交换场强度都高于极性失配的超晶格.上述研究结果对进一步理解钙钛矿超晶格中的磁电输运性能有所帮助.Perovskite superlattices have received enormous attention in recent years,for they possess several new phases of quantum matter.In particular,an unexpected exchange bias effect in(111)-oriented superlattices composed of ferromagnetic LaMnO_(3) and paramagnetic LaNiO_(3) is observed,which has aroused broad interest.In this work,three kinds of LaMnO_(3)/LaNiO_(3) superlattices with(001),(110),and(111) out-of-plane orientation are fabricated by pulsed laser deposition,and also studied systemically.It is found that the superlattices are epitaxially grown on the SrTiO_(3) substrates without strain relaxation.The superlattices have a monolayer terraced structure with a surface roughness below 0.1 nm.Electrical transport measurements reveal a Mott conducting behavior with strong localization of electrons in the superlattices.All the superlattices with different orientations exhibit exchange bias phenomenon.The field cooling and zero field cooling curves indicate that there are two different magnetic components in the superlattice in a low temperature range.Further analysis of the values of exchange field reveals that the exchange bias field is related to the orientation and polarity of the superlattices.Different superlattices form different charged planes stacked along out-of-plane orientation,leading to a polarity match/mismatch at the interface between the superlattices and substrates.The surface reconstructions that act as compensating for the polar mismatch influence the exchange bias field of the superlattices.It is observed that the intensities of the exchange field of the polar-matched superlattices are higher than those of the polar-mismatched superlattices at different temperatures.These results are helpful in further understanding the magnetoelectric transport properties in the perovskite superlattices.

关 键 词：钙钛矿 超晶格 外延生长 交换偏置 

分 类 号：TB34[一般工业技术—材料科学与工程] O469[理学—凝聚态物理]