手性超导体4Hb-TaS_(2)的开尔文探针力显微术研究

Kelvin Probe Force Microscopy Study on Chiral Superconductor 4Hb-TaS_(2)

范德瓦尔斯材料是一类由数层相同或不同的共价键原子薄层通过层间微弱的范德华相互作用连接起来的新型薄层材料,其中由超导体1H-TaS_(2)和莫特绝缘体1T-TaS_(2)交替堆叠而成的4Hb-TaS_(2)因其独特的二维层状结构、优良的电子特性和特殊的层间电荷转移备受关注。目前关于如何调控这种特殊层间电荷转移的研究较少,使得4Hb-TaS_(2)的电学性质仍然有较大的研究空间。在文章中,以开尔文探针力显微术(KPFM)为表征手段,研究了4Hb-TaS_(2)的表面电势差,结合表面形貌信息可以实现对其表面解理层的分辨。通过高温退火实现了T-H转化,成功制备了4Hb-Ta1-xTixS_(2)(x=0.005),并在此基础上探究了不同元素掺杂对4Hb-TaS_(2)表面电学性质的影响。研究发现,通过掺杂不同元素,能够调控4Hb-TaS_(2)中层间电荷转移能力,影响其表面电势差的大小,Ti掺杂后4Hb-TaS_(2)的表面电势差明显增大,而Se掺杂后表面电势差减小。此外,研究发现4Hb-TaS_(2)除了T层、H层正常交替堆垛外,还存在部分堆垛层错的现象。实现层间电荷转移的可控调控对进一步探究4Hb-TaS_(2)的层间电荷转移具有一定的帮助,同时也对其他范德瓦尔斯材料的层间电荷转移和表面电学性质的研究提供了新启发。

Van der Waals material is a new kind of thin material,which is connected by several thin layers of covalent bonds of the same or different atoms through weak van der Waals interaction between layers.4Hb-TaS_(2),which is alternately stacked by superconductor 1H-TaS_(2)and Mott insulator 1T-TaS_(2),has attracted much attention because of its unique two-dimensional layered structure,excellent electronic properties and special interlayer charge transfer.At present,there is little research on how to regulate this special interlayer charge transfer,which makes the electrical properties of 4Hb-TaS_(2)still have a large research space.In this paper,the surface potential difference of 4Hb-TaS_(2)was studied by means of Kelvin probe force microscopy(KPFM),and the cleavage layer on its surface can be distinguished by combining the surface morphology information.T-H transformation was realized by high temperature annealing,and 4Hb-Ta1-xTixS_(2)(x=0.005)was successfully prepared.On this basis,the influence of different element doping on the surface electrical properties of 4Hb-TaS_(2)was explored.It is found that by doping different elements,the interlayer charge transfer ability of 4Hb-TaS_(2)can be controlled and the surface potential difference can be affected.The surface potential difference of 4Hb-TaS_(2)is obviously increased after Ti doping,but it is decreased after Se doping.In addition,it is found that 4Hb-TaS_(2)is not only stacked alternately in T layer and H layer,but also has some stacking faults.The controllable regulation of interlayer charge transfer provides help for the in-depth study of interlayer charge transfer of this system material.At the same time,it also provides new inspiration for the study of interlayer charge transfer and surface electrical properties of other van der Waals materials.