Inverted Resistance Measurements as a Method for Characterizing the Bulk and Surface Conductivities of Three-Dimensional Topological Insulators
Inverted Resistance Measurements as a Method for Characterizing the Bulk and Surface Conductivities of Three-Dimensional Topological Insulators
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DOI：
10.1103/physrevapplied.9.044006
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发表时间：
2018-04-05
影响因子：
4.6
通讯作者：
Fisk, Z.
中科院分区：
文献类型：
--
作者：
Eo, Y. S.;Sun, K.;Fisk, Z.
我们介绍了一种电阻测量方法，这是有用的表征材料的表面和体导电，如三维拓扑绝缘体。该电阻测量配置的传输几何结构由一根电流引线和两根电压引线组成，其中一根电流引线作为闭合回路，完全包围表面上的另一根电流引线，两根电压引线均放置在回路外部。我们表明，在传输是由材料的表面电导率占主导地位的限制，从这样的传输几何测量的四端电阻是成比例的sigma（B）/sigma（2）（s），其中sigma（B）和sigma（s）是体和表面电导率的材料，分别。我们称这种类型的测量为反向电阻测量，因为电阻与体电阻率成反比。我们讨论了这种方法的可能实现，通过对不同的几何形状进行数值计算，并引入策略来提取体和表面电导率。我们还展示了SmB 6，拓扑近藤绝缘体，使用单面和同轴对齐的双面科尔比诺磁盘传输几何的反转电阻测量。使用这种方法，我们能够测量体电导率，即使在低温下，其中体电导率比该材料的表面电导率小得多。
We introduce a resistance measurement method that is useful in characterizing materials with both surface and bulk conduction, such as three-dimensional topological insulators. The transport geometry for this resistance measurement configuration consists of one current lead as a closed loop that fully encloses the other current lead on the surface, and two voltage leads that are both placed outside the loop. We show that, in the limit where the transport is dominated by the surface conductivity of the material, the four-terminal resistance measured from such a transport geometry is proportional to sigma(b)/sigma(2)(s), where sigma(b) and sigma(s) are the bulk and surface conductivities of the material, respectively. We call this type of measurement inverted resistance measurement, as the resistance scales inversely with the bulk resistivity. We discuss possible implementations of this method by performing numerical calculations on different geometries and introduce strategies to extract the bulk and surface conductivities. We also demonstrate inverted resistance measurements on SmB6, a topological Kondo insulator, using both single-sided and coaxially aligned double-sided Corbino disk transport geometries. Using this method, we are able to measure the bulk conductivity, even at low temperatures, where the bulk conduction is much smaller than the surface conduction in this material.