MgO基磁性隧道结中隧穿磁-塞贝克效应温度特性的理论研究  

Theoretical Study of the Temperature Characteristics of the Tunnel Magneto-Seebeck Effect in MgO-based Magnetic Tunnel Junctions

作　　者：刘超[1] 陶懿洲 方贺男[1] LIU Chao;TAO Yizhou;FANG He nan(College of Electronic and Optical Engineering&College of Flexible Electronics(Future Technology),Nanjing University of Posts and Telecommunications,Nanjing 210023,CHN)

机构地区：[1]南京邮电大学电子与光学工程学院、柔性电子(未来技术)学院,南京210023

出　　处：《半导体光电》2024年第5期798-804,共7页Semiconductor Optoelectronics

基　　金：国家自然科学基金项目(11704197);南京邮电大学校级自然科学基金项目(NY221066,NY223074).

摘　　要：构建了基于光学方法的单晶势垒层磁性隧道结理论模型,并利用该模型研究了MgO基磁性隧道结中隧穿磁-塞贝克效应的温度特性。由于该理论模型充分地计入了势垒层的周期性和晶格畸变的影响,在此理论模型中,温度不仅通过费米分布函数对塞贝克系数产生影响,还会通过晶格畸变对塞贝克系数进行修正,进而使塞贝克系数具有关于温度的振荡特性。该振荡特性来源于单晶势垒层周期势对隧穿电子的衍射所导致的相干性。上述结果在理论上解释了MgO基磁性隧道结中平行塞贝克系数和TMS随温度非单调变化的实验结果,并阐明了其物理机制。此外,文章还研究了应变、杂质浓度以及回复温度等晶格畸变参数对隧穿磁-塞贝克效应温度特性的影响。研究结果发现,杂质浓度和回复温度可以对平行塞贝克系数非单调变化的幅度进行调制。A spintronic theory is proposed for a magnetic tunnel junction with a single-crystal barrier.This theory is founded on optical theory and the Patterson function approach and can adequately account for the influences of the barrier periodicity and lattice distortion.Based on the proposed theory,we investigated the temperature characteristics of the tunnel magneto-Seebeck effect in MgO-based magnetic tunnel junctions.In low-temperature approximation,the temperature only influences the Seebeck coefficients through the Fermi distribution function.However,in the proposed theory,the temperature can modify the potential parameter of the barrier through lattice distortion and further alter the Seebeck coefficients.As the tunneling electrons are scattered by the single-crystal barrier,the corresponding coherence leads to the oscillation of the Seebeck coefficients.The results can theoretically interpret the non-monotonic temperature characteristics of the Seebeck coefficient in the parallel configuration and TMS in MgO-based magnetic tunnel junctions.Furthermore,the physical mechanism of the non-monotonic temperature characteristics is elucidated.In addition,we investigated the influences of the parameters of the lattice distortion,such as strain,defect concentration,and recovery temperature,on the temperature characteristics of the tunnel magneto-Seebeck effect.It is found that the amplitudes of the non-monotonic variations of the Seebeck coefficient in the parallel configuration can be modulated by the defect concentration and recovery temperature.

关 键 词：磁性隧道结 隧穿磁-塞贝克效应 晶格畸变 自旋热电子学 

分 类 号：O482.5[理学—固体物理]