Composition and temperature-dependent phase transition in miscible Mo(1-x)W(x)Te(2) single crystals.
Composition and temperature-dependent phase transition in miscible Mo(1-x)W(x)Te(2) single crystals.
复制标题
易混溶 Mo1–xWxTe2 单晶的成分和温度依赖性相变
DOI：
10.1038/srep44587
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发表时间：
2017-03-15
影响因子：
4.6
通讯作者：
Chen YF
中科院分区：
文献类型：
--
作者：
Lv YY;Cao L;Li X;Zhang BB;Wang K;Bin Pang;Ma L;Lin D;Yao SH;Zhou J;Chen YB;Dong ST;Liu W;Lu MH;Chen Y;Chen YF
具有正交晶系TD相的过渡金属二卤化物(TMDs)WTe2和MoTe2作为二类Weyl半金属化合物的潜在候选者，近年来受到了广泛的关注。本文采用溴蒸气输运法制备了一系列可混溶的Mo_1-−_xW_xTe_2单晶。成分相关的X射线衍射和拉曼光谱以及成分和温度相关的电阻率证明，增加Mo_1xW_xTe_2中的W含量可以实现晶体结构的可调(从六方相(2H)、单斜相(β)到正交相(TD))。同时，电学性质也逐渐从半导体演化为半金属行为。变温拉曼光谱证明，温度也能诱导Mo_1WxWxTe_2晶体从β相到TD相的结构相变。−_xW_xTe_2晶体的结构相变。在上述表征的基础上，我们绘制了Mo_1-−_xW_xTe_2系的温度和成分相关相图。此外，还给出了载流子类型、载流子浓度和迁移率等一系列电学参数。本工作提供了一种精确控制Mo1-−-xWxTe2体系结构相的方案，可用于探索第二类Weyl半金属以及其中的温度/成分控制的拓扑相变。
Transition metal dichalcogenides (TMDs) WTe2 and MoTe2 with orthorhombic Td phase, being potential candidates as type-II Weyl semimetals, are attracted much attention recently. Here we synthesized a series of miscible Mo1−xWxTe2 single crystals by bromine vapor transport method. Composition-dependent X-ray diffraction and Raman spectroscopy, as well as composition and temperature-dependent resistivity prove that the tunable crystal structure (from hexagonal (2H), monoclinic (β) to orthorhombic (Td) phase) can be realized by increasing W content in Mo1−xWxTe2. Simultaneously the electrical property gradually evolves from semiconductor to semimetal behavior. Temperature-dependent Raman spectroscopy proves that temperature also can induce the structural phase transition from β to Td phase in Mo1−xWxTe2 crystals. Based on aforementioned characterizations, we map out the temperature and composition dependent phase diagram of Mo1−xWxTe2 system. In addition, a series of electrical parameters, such as carrier type, carrier concentration and mobility, have also been presented. This work offers a scheme to accurately control structural phase in Mo1−xWxTe2 system, which can be used to explore type-II Weyl semimetal, as well as temperature/composition controlled topological phase transition therein.