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arXiv 2101.08952cond-mat.mes-hall
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少层1 T '和Td MoTe2的结构相变和层间耦合

Structural Phase Transition and Interlayer Coupling in Few-Layer 1T' and Td MoTe2

Yeryun Cheon, Soo Yeon Lim, Kangwon Kim, Hyeonsik Cheong

摘要:

我们对机械剥离的少层MoTe_2样品进行了偏振拉曼光谱分析,在室温下观察到了1 T '和Td相。少层1 T '和Td MoTe 2表现出显着的差异,特别是在层间振动模式,从中提取的层间耦合强度使用线性链模型:在两个阶段中观察到强的面内各向异性。此外,温度相关的拉曼光谱测量揭示了一个特殊的相变行为在少层1 T 'MoTe 2。与在~250 K下发生向Td相的相变的大块1 T 'MoTe 2晶体相比,随着厚度的减小,温度驱动的向Td相的相变越来越受到抑制,并且即使对于相同的厚度,从样品到样品的转变和临界温度也显著变化。观察到了既不对应于1 T '相也不对应于Td相的中间相的Raman光谱,这些中间相具有不同的层间振动模式,这表明存在几个亚稳相,它们的总能量相似。

英文摘要:

We performed polarized Raman spectroscopy on mechanically exfoliated few-layer MoTe2 samples and observed both 1T' and Td phases at room temperature. Few-layer 1T' and Td MoTe2 exhibited a significant difference especially in interlayer vibration modes, from which the interlayer coupling strengths were extracted using the linear chain model: strong in-plane anisotropy was observed in both phases. Furthermore, temperature-dependent Raman measurements revealed a peculiar phase transition behavior in few-layer 1T' MoTe2. In contrast to bulk 1T' MoTe2 crystals where the phase transition to the Td phase occurs at ~250 K, the temperature-driven phase transition to the Td phase is increasingly suppressed as the thickness is reduced, and the transition and the critical temperature varied dramatically from sample to sample even for the same thickness. Raman spectra of intermediate phases that correspond to neither 1T' nor Td phase with different interlayer vibration modes were observed, which suggests that several metastable phases exist with similar total energies.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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