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arXiv 1702.04794cond-mat.str-el
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$β$ $_4$ I $_4$拓扑绝缘体中的压力效应和超导电性

Pressure effect and Superconductivity in $β$-Bi$_4$I$_4$ Topological Insulator

A. Pisoni, R. Gaal, A. Zeugner, V. Falkowski, A. Isaeva, H. Huppertz, G. Autes, O. V. Yazyev, L. Forro

摘要:

本文详细研究了准一维拓扑绝缘体的$β$ -Bi $_4$ I $_4$的输运系数.电阻率,热电功率,热导率和霍尔系数的测量是一致的,在低温下的电荷密度波顺序的可能外观。电子和空穴都有助于$β$/$_4$中的传导,并且由于温度依赖的载流子密度和迁移率,载流子的主要类型随温度而变化。电阻率和Seebeck系数的测量静水压力下高达2 GPa的电荷密度波的顺序,以更高的温度表明在环境压力下强烈的一维字符的移位。令人惊讶的是,在高于10 GPa的4.0 K下,在$β$ $_4$ I $_4$中诱导超导性,当压力增加到20 GPa时,该温度略微降低.经压力处理的样品的化学表征表明,$β$ -Bi $_4$ I $_4$在压力下发生非晶化,并排除了在室温条件下分解成Bi和Bi I $_3$的可能性。

英文摘要:

We report a detailed study of the transport coefficients of $β$-Bi$_4$I$_4$ quasi-one dimensional topological insulator. Electrical resistivity, thermoelectric power, thermal conductivity and Hall coefficient measurements are consistent with the possible appearance of a charge density wave order at low temperatures. Both electrons and holes contribute to the conduction in $β$-Bi$_4$I$_4$ and the dominant type of charge carrier changes with temperature as a consequence of temperature-dependent carrier densities and mobilities. Measurements of resistivity and Seebeck coefficient under hydrostatic pressure up to 2 GPa show a shift of the charge density wave order to higher temperatures suggesting a strongly one-dimensional character at ambient pressure. Surprisingly, superconductivity is induced in $β$-Bi$_4$I$_4$ above 10 GPa with of 4.0 K which is slightly decreasing upon increasing the pressure up to 20 GPa. Chemical characterisation of the pressure-treated samples shows amorphization of $β$-Bi$_4$I$_4$ under pressure and rules out decomposition into Bi and BiI$_3$ at room-temperature conditions.

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