Electric double-layer transistor using layered iron selenide Mott insulator TlFe1.6Se2
Electric double-layer transistor using layered iron selenide Mott insulator TlFe1.6Se2
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DOI：
10.1073/pnas.1318045111
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发表时间：
2014-03-18
影响因子：
11.1
通讯作者：
Hosono, Hideo
中科院分区：
文献类型：
--
作者：
Katase, Takayoshi;Hiramatsu, Hidenori;Hosono, Hideo
A(1-x)Fe(2-y)Se(2)（A = K、Cs、Rb、Tl）是最近发现的铁基超导体，其临界温度（T-c）高达32 K。与其他铁基超导体相比，其母相具有独特的性能； e.例如，它们的晶体结构包括有序的铁空位，它们的正常状态是反铁磁（AFM）绝缘相，并且它们具有极高的尼尔转变温度。然而，由于 AFM 绝缘体固有的相分离，控制载流子掺杂一直很困难。在这里，我们制造了具有原子级平坦表面的 Fe 空位有序 TlFe1.6Se2 绝缘外延薄膜，并使用带有离子液体栅极的电双层晶体管（EDLT）结构检查了其静电载流子掺杂。正栅极电压在 25 K 时产生三个数量级的电导调制，并进一步诱导和操纵相变；即，静电掺杂产生的离域载流子是相变的根源。据作者所知，这是使用莫特绝缘体硒化铁通道的 EDLT 的首次演示，并为探索铁基层状材料中的高 T-c 超导性开辟了一条道路，而在铁基层状材料中通过传统化学方法进行载流子掺杂是困难的。
A(1-x)Fe(2-y)Se(2) (A = K, Cs, Rb, Tl) are recently discovered iron-based superconductors with critical temperatures (T-c) ranging up to 32 K. Their parent phases have unique properties compared with other iron-based superconductors; e. g., their crystal structures include ordered Fe vacancies, their normal states are antiferromagnetic (AFM) insulating phases, and they have extremely high Neel transition temperatures. However, control of carrier doping into the parent AFM insulators has been difficult due to their intrinsic phase separation. Here, we fabricated an Fe-vacancy-ordered TlFe1.6Se2 insulating epitaxial film with an atomically flat surface and examined its electrostatic carrier doping using an electric double-layer transistor (EDLT) structure with an ionic liquid gate. The positive gate voltage gave a conductance modulation of three orders of magnitude at 25 K, and further induced and manipulated a phase transition; i.e., delocalized carrier generation by electrostatic doping is the origin of the phase transition. This is the first demonstration, to the authors' knowledge, of an EDLT using a Mott insulator iron selenide channel and opens a way to explore high T-c superconductivity in iron-based layered materials, where carrier doping by conventional chemical means is difficult.