不同氮流量制备Mn3CuNx薄膜及其电、磁输运性质的研究

采用对靶磁控溅射方法在单晶Si(100)基片上制备了反钙钛矿结构的Mn₃CuN_x薄膜.通过控制制备过程中的反应气体氮气(N₂) 流量(N₂/Ar+N₂), 研究了氮含量对Mn₃CuN_x薄膜结构及物理性能的影响.分别利用X射线衍射仪、俄歇电子能谱、 原子力显微镜、X射线光电子能谱、物理性能测试系统和超导量子干涉仪, 对所制备薄膜的晶体结构、成分、表面形貌和电、磁输运性质进行了测试.结果表明:制备的薄膜均为反钙钛矿立方结构,且沿 (200) 晶面择优生长.随着氮含量的增大,薄膜表面粗糙度和颗粒度尺寸逐渐增大, 导致电阻率增加.氮含量对薄膜的电输运性质没有影响,所有薄膜电阻率均随着温度的降低逐渐增大, 呈现半导体型导电行为,这与对应的块体材料结果相反.Mn₃CuN_x薄膜随着测试温度的增大发生了 亚铁磁到顺磁的磁转变,且N含量的增大降低了磁有序转变温度,主要是由于N缺陷对Mn₆N八面体结构中 磁交换作用的影响所致.

Study on electronic transport and magnetic properties for antiperovskite Mn3CuNx thin films fabricated with different N2 flow rates

The antiperovskite Mn₃CuN_x thin films are successfully deposited on single crystal Si (100) substrates using facing target magnetron sputtering. The effects of nitrogen content on the structures and physical properties of the Mn₃CuN_x thin films are investigated. The crystal structure, composition, surface morphology and the temperature dependence of resistivity and magnetization are characterized by X-ray diffraction, Auger electron spectroscopy, atomic force microscope, X-ray photoelectron spectroscopy, physical property measurement systems and superconducting quantum interference device. It is found that the thin film has an antiperovskite structure and a preferred orientation along (200) plane. The surface roughness and particle size increase with N content increasing. N content has little influence on the electronic transport behavior of the film. All the films display semiconductor-like behaviors, i.e. their resistivities monotonically decrease considerably, which is different from the bulk counterpart. The film undergoes a magnetic transition from ferrimagnetic to paramagnetic with the increase of temperature. Moreover, the Curie temperature (T_C) increases as the N content decreases, owing to the effect of N deficiency on the interaction of Mn₆N octahedron.