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Studies on Shubnikov-de Haas oscillations and magnetic properties of cobalt-doped Bi1.9Co0.05 Sb0.05Se3 topological single crystals
Journal of Alloys and Compounds ( IF 6.2 ) Pub Date : 2019-02-01 , DOI: 10.1016/j.jallcom.2018.10.107
E.P. Amaladass , A.T. Satya , Shilpam Sharma , K. Vinod , Awadhesh Mani

Abstract Magnetotransport and magnetic properties of pristine Bi1.9Sb0.1Se3 (BSS) and Co-doped Bi1.9Co0.05Sb0.05Se3 (BCSS) topological insulator (TI) single crystals are reported. Both the samples show metallic behavior, but the overall resistivity decreases upon Co doping. Temperature and field dependent magnetization, M (H) and M (T) measurements on BSS exhibit diamagnetic nature from 2.8 K to 300 K. Whereas at T ≤ 10 K, Co-doped sample shows a paramagnetic behavior in low field range and a diamagnetic behavior at H ≥ ±3.5 T. The analysis of M (H) and M (T) data reveals that Co2+ and Co3+ might coexist in the diamagnetic matrix. Hall measurements indicate that the carriers are n-type and its density increases by one order of magnitude upon Cobalt doping. The Hall mobility decreases in BCSS, and its temperature dependence shows an increasing behavior as the temperature decreases in both the samples. The Shubnikov-de Haas (SdH) oscillations have been analyzed using Lifshitz-Kosovich (LK) equation. The frequency of SdH oscillation drastically increases for BCSS pointing to the fact that the Fermi energy (EF) is shifted upward and the mobility of surface state electrons decreases. The substituted Co atoms act as paramagnetic entities and are found to be strong electron donors as well as strong scattering centers. The Berry curvature β derived from LK fit increases from 0.56 to 0.8 upon Co doping and shows the contribution of non-Dirac like bands to the SdH oscillations.

中文翻译:

掺钴Bi1.9Co0.05 Sb0.05Se3拓扑单晶的Shubnikov-de Haas振荡和磁性能研究

摘要 报道了原始 Bi1.9Sb0.1Se3 (BSS) 和 Co 掺杂 Bi1.9Co0.05Sb0.05Se3 (BCSS) 拓扑绝缘体 (TI) 单晶的磁输运和磁性能。两个样品都显示出金属行为,但在 Co 掺杂后整体电阻率降低。BSS 上的温度和场相关磁化强度、M (H) 和 M (T) 测量显示出从 2.8 K 到 300 K 的抗磁性。而在 T ≤ 10 K 时,Co 掺杂样品在低场范围内表现出顺磁行为和抗磁性在 H ≥ ±3.5 T 时的行为。 M (H) 和 M (T) 数据的分析表明 Co2+ 和 Co3+ 可能共存于抗磁基质中。霍尔测量表明载流子是 n 型的,并且在钴掺杂后其密度增加了一个数量级。BCSS 中霍尔迁移率降低,并且其温度依赖性显示出随着两个样品中温度降低而增加的行为。已使用 Lifshitz-Kosovich (LK) 方程分析了 Shubnikov-de Haas (SdH) 振荡。BCSS 的 SdH 振荡频率急剧增加,这表明费米能量 (EF) 向上移动并且表面态电子的迁移率降低。取代的 Co 原子充当顺磁实体,并且被发现是强电子供体以及强散射中心。在 Co 掺杂后,从 LK 拟合得出的 Berry 曲率 β 从 0.56 增加到 0.8,并显示了非狄拉克带对 SdH 振荡的贡献。BCSS 的 SdH 振荡频率急剧增加,这表明费米能量 (EF) 向上移动并且表面态电子的迁移率降低。取代的 Co 原子充当顺磁实体,并且被发现是强电子供体以及强散射中心。在 Co 掺杂后,从 LK 拟合得出的 Berry 曲率 β 从 0.56 增加到 0.8,并显示了非狄拉克带对 SdH 振荡的贡献。BCSS 的 SdH 振荡频率急剧增加,这表明费米能量 (EF) 向上移动并且表面态电子的迁移率降低。取代的 Co 原子充当顺磁实体,并且被发现是强电子供体以及强散射中心。在 Co 掺杂后,从 LK 拟合得出的 Berry 曲率 β 从 0.56 增加到 0.8,并显示了非狄拉克带对 SdH 振荡的贡献。
更新日期:2019-02-01
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