Er掺杂MnBi_(2)Te_(4)晶体生长及其微结构研究

Growth and Microstructure of Er-Doped MnBi_(2)Te_(4)Crystal

MnBi_(2)Te_(4)是首次被发现的一种本征磁性拓扑绝缘体,具有重要的研究意义。本文通过在MnBi_(2)Te_(4)晶体中进行稀土元素掺杂,合成了Er掺杂MnBi_(2)Te_(4)晶体,Er原子进入晶格并取代Mn位。在晶体制备过程中,考虑到目前晶体制备工艺周期较长,生成物存在Bi_(2)Te_(3)助熔剂等杂质的问题,对晶体制备工艺进行了优化探索。XRD测试结果表明,利用改进工艺制备的Er掺杂MnBi_(2)Te_(4)晶体结晶性能良好,不含杂质相。磁电输运测量结果显示,少量Er掺杂MnBi_(2)Te_(4)晶体的磁性增强,掺杂样品在25.2 K发生反铁磁相变。使用原子力显微镜对Er掺杂MnBi_(2)Te_(4)晶体层间距进行了研究,发现层间距为单层MnBi_(2)Te_(4)的整数倍。通过拉曼测试研究了Er掺杂MnBi_(2)Te_(4)晶体声子振动模式,结果表明,Er掺杂是调节MnBi_(2)Te_(4)磁性的一种可行方法。

MnBi_(2)Te_(4)is an intrinsic magnetic topological insulator discovered for the first time,which has important research significance.In this paper,Er-doped MnBi_(2)Te_(4)crystal were synthesized by doping rare earth elements in MnBi_(2)Te_(4)crystal.The Er atom enters the lattice and replaces the Mn site.Considering the long period of crystal preparation process and the existence of impurities such as Bi_(2)Te_(3)flux in the product during crystal preparation,the crystal preparation process was optimized.XRD analysis shows that the Er-doped MnBi_(2)Te_(4)crystal prepared by the optimized process has good crystallinity and no impurity phase.The magnetoelectric transport measurement results show that a small amount of Er-doped MnBi_(2)Te_(4)crystal has enhanced magnetic properties,and the doped samples undergo antiferromagnetic phase transition at 25.2 K.The layer spacing of Er-doped MnBi_(2)Te_(4)crystal was studied by atomic force microscopy.The layer spacing is an integral multiple of that of single-layer MnBi_(2)Te_(4).The phonon vibration mode of Er-doped MnBi_(2)Te_(4)crystal was studied by Raman measurement,and the results show that doping Er is a feasible method to adjust the magnetic properties of MnBi_(2)Te_(4).