分子束外延Mn_(4)N单晶薄膜的反常霍尔效应研究  

Study on the anomalous Hall effect in Mn_(4)N single crystal films grown by molecular beam epitaxy

作　　者：黄盈 赵治贤 胡雍 李丹[1] HUANG Ying;ZHAO Zhi-Xian;HU Yong;LI Dan(Guizhou Normal University,Guiyang 550025,China)

机构地区：[1]贵州师范大学,贵阳550025

出　　处：《原子与分子物理学报》2023年第6期60-66,共7页Journal of Atomic and Molecular Physics

基　　金：贵州省联合基金项目(黔科合J-LKS[2013]15号)。

摘　　要：Mn_(4)N是立方相的反钙钛矿型晶体,具有显著的亚铁磁性和反常霍尔效应.该文利用等离子辅助分子束外延在MgO(100)衬底上生长厚度为40 nm的Mn_(4)N(100)单晶薄膜,通过X射线衍射θ扫描和φ扫描,证实外延层的结构符合Mn_(4)N单晶的空间结构特征;化学态测试结果表明Mn_(4)N(100)薄膜内部存在Mn^(0)、Mn^(2+)和Mn^(4+)等几种价态,其实际化学式为Mn_(3.6)N,薄膜中存在富余的N元素;电学测试数据表明Mn_(4)N(100)薄膜具有以电子为载流子的反常霍尔效应(在正磁场中得到负的霍尔电阻率),正常霍尔效应的贡献约占千分之六,其反常霍尔电阻率随着测试温度升高5 K~350 K单调增大,说明温度升高导致电子散射现象加剧.通过对测试数据分析可以推断,在5 K~50 K和50 K~75 K温度范围,反常霍尔效应的来源可分别归结为电子斜散射机制和电子边跳机制.在75 K~350 K这一温度范围内,反常霍尔效应主要来源于与能带结构相关的内禀机制.Mn_(4)N is categorized to cubic anti-perovskite crystal structure with obvious ferromagnetism and anomalous Hall effects.About 40 nm of mono-crystalline Mn_(4)N(100)films have been grown on MgO(100)substrates by plasma-assisted molecular beam epitaxy.The spatial structure of the epitaxial layers is found to be consistent with the structural features of Mn_(4)N crystal lattice through X-ray diffractionθscanning andφscanning.Various valence states Mn,such as Mn^(0),Mn^(2+),and Mn^(4+),are observed to coexist in the Mn_(4)N(100)specimens by the test of X-ray photoelectron spectroscopy.The actual chemical formula of the specimen is calculated to be Mn_(3.6)N according to the XPS quantitative data.Noticeable electron-type anomalous Hall effects(negative Hall resistivity in positive magnetic fields)are demonstrated by the test results of physical property measurement systems(PPMS).The Hall resistance curve grows monotonically as test temperature rises from 5 K to 350 K,which shows reinforcement of scattering of electrons.The contribution of normal Hall effects is fitted to be about 6 per thousand of the total Hall data.Summarily,the anomalous Hall effects in temperature range of 5 K~50 K and 50 K~75 K are originated from extrinsic skew scattering mechanism and side-jump mechanism,respectively.The anomalous Hall effects in higher temperature range of 75 K~350 K are originated from band-structure-related intrinsic mechanism.

关 键 词：反常霍尔效应 Mn_(4)N单晶薄膜 分子束外延 

分 类 号：O482.54[一般工业技术—材料科学与工程]