Two Linear Regimes in Optical Conductivity of a Type-I Weyl Semimetal: The Case of Elemental Tellurium
Two Linear Regimes in Optical Conductivity of a Type-I Weyl Semimetal: The Case of Elemental Tellurium
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DOI：
10.1103/physrevlett.124.136402
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发表时间：
2020-03-30
影响因子：
8.6
通讯作者：
Uykur, Ece
中科院分区：
文献类型：
--
作者：
Rodriguez, Diego;Tsirlin, Alexander A.;Uykur, Ece
采用高压红外光谱，我们揭示了外尔半金属相的元素Te和它的拓扑性质。光学电导率的线性频率依赖性为三角碲（Te-I）的金属化和3.0 GPa以上的线性带色散提供了明确的证据。这种半金属外尔相可以通过进一步增加压力来调整：扭结将光学电导率（在3.7 GPa下）的两个线性区域分开，这是具有倾斜锥体的II型外尔半金属的签名;然而，这揭示了三角碲的不同起源。我们的密度泛函计算没有发现任何显着的倾斜，并建议Te-I保持在I型外尔相，但在费米能级附近的两个价带。它们之间的相互作用导致了具有不止一个线性区域的奇特的光学电导率行为。高于4.3GPa的压力稳定了更复杂的Te-II和Te-III多晶型物，这是坚固的金属。
Employing high-pressure infrared spectroscopy we unveil the Weyl semimetal phase of elemental Te and its topological properties. The linear frequency dependence of the optical conductivity provides clear evidence for metallization of trigonal tellurium (Te-I) and the linear band dispersion above 3.0 GPa. This semimetallic Weyl phase can be tuned by increasing pressure further: a kink separates two linear regimes in the optical conductivity (at 3.7 GPa), a signature proposed for Type-II Weyl semimetals with tilted cones; this however reveals a different origin in trigonal tellurium. Our density-functional calculations do not reveal any significant tilting and suggest that Te-I remains in the Type-I Weyl phase, but with two valence bands in the vicinity of the Fermi level. Their interplay gives rise to the peculiar optical conductivity behavior with more than one linear regime. Pressure above 4.3 GPa stabilizes the more complex Te-II and Te-III polymorphs, which are robust metals.