摘要
钙钛矿超晶格材料界面的独特电子性质,在纳米器件、新型超敏传感器器件等方面具有广阔的应用前景,探索其界面独特的电子性质对理解关联电子系统中多自由度耦合和传感器器件的设计等方面具有重要的意义.本文通过构建LaAlO_(3)/KNbO_(3)超晶格材料,施加非均匀应变对其界面的载流子浓度等性质进行调控.计算结果表明,施加拉伸和压缩的应变梯度都可以调节界面处二维电子气性质.其中,当最大压缩应变梯度系数为12%时,界面处二维电子气浓度减小了76.4%,并且界面磁矩消失,材料的总磁矩减小约88.44%,向无磁性材料转变;当最大拉伸型应变梯度系数为12%时,界面处电子气浓度增大约23.9%,界面磁矩明显减小,而且界面临近层出现明显的磁矩.该理论计算结果表明,应变梯度是一种新的钙钛矿界面载流子的有效调控手段,对LaAlO_(3)/KNbO_(3)钙钛矿超晶格材料界面电子性质的研究提升了对此类氧化物界面电子特性的认识,为探索调控氧化物界面处的高性能自旋极化载流子气开辟了新的途径.
The superlattices composed of polar/polar perovskites have two-dimensional electron gas(2DEG)at the interface,which has broad applications in nano devices,super sensitive sensor devices,high electron mobility transistor,etc.Tuning the electronic properties of the 2DEG at the interface perovskite superlattice,such as the coupling between strain gradient and the electronic properties of the 2DEG in correlated electronic systems,is of great significance.In this paper,the properties of(LaAlO_(3))4.5/(KNbO_(3))8.5 superlattice,which is composed of KNbO_(3) and LaAlO_(3),are systematically investigated through first-principles density functional theory calculations.The band structure of(LaAlO_(3))4.5/(KNbO_(3))8.5 superlattice exhibits 2DEG at the interface,which is consistent with the result in the literature.The band structure,density of states,magnetic moments and carrier concentration at the interface are fully investigated by using compressive gradient and tensile strain gradient,respectively.The results show that compressive strain gradient can effectively reduce the 2DEG concentration at the interface.When the compressive strain gradient coefficient reaches 12%,the 2DEG concentration decreases by 76.4%,and the interface magnetic moment disappears.The total magnetic moment of the superlattice decreases by 88.44%.When the tensile strain gradient is 12%,the electron gas concentration at the interface is increased by about 23.9%,and the interface magnetic moment is reduced by about 90.7%.At the same time,an obvious magnetic moment appears in the layer near the interface.Hence,the strain gradient can be a new approach to regulating the electron gas concentration at interface of perovskite superlattice.The tensile strain gradient increases the electron gas concentration at the interface,while the compressive strain gradient reduces the electron gas concentration.Therefore,it opens up a new way to exploring the regulation of high-performance spin polarized carrier gas at the oxide interface.
作者
王继光
李珑玲
邱嘉图
陈许敏
曹东兴
Wang Ji-Guang;Li Long-Ling;Qiu Jia-Tu;Chen Xu-Min;Cao Dong-Xing(School of Science,Hangzhou Dianzi University,Hangzhou 310018,China;Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第17期289-297,共9页
Acta Physica Sinica
基金
国家自然科学基金(批准号:11874011,11972051)资助的课题.
关键词
应变梯度
二维电子气
超晶格
第一性原理
strain gradient
two-dimensional electron gas
superlattice
first principles
