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Quasi-two-dimensional heterostructures (KM1 (-) Te-x)(LaTe{s


Bao, Jin-Ke; Malliakas, Christos; Zhang, Chi; Cai, Songting; Chen, Haijie; Rettie, Alexander; Fisher, Brandon; Chung, Duck Young; Dravid, Vinayak ; Kanatzidis, Mercouri


Layered heterostructure materials with two different functional building blocks can teach us about emergent physical properties and phenomena arising from interactions between the layers. We report intergrowth compounds KLaM1 - xTe4 (M = Mn and Zn; x approximate to 0.35) featuring two chemically distinct alternating layers [LaTe and [KM1 - xT. Their crystal structures are incommensurate, determined by single X-ray diffraction for the Mn compound and a transmission electron microscope study for the Zn compound. KLaMn1 (-) Te-x(4) crystallizes in the orthorhombic superspace group Pmnm(01/2 gamma)s00 with lattice parameters a = 4.4815(3) A, b = 21.6649(16) A, and c = 4.5220(3) A. It exhibits charge density wave order at room temperature with a modulation wave vector q = 1/2b* + 0.3478c* originating from electronic instability of Te-square nets in [LaTe layers. The Mn analog exhibits a cluster spin glass behavior with spin freezing temperature T-f approximate to 5 K attributed to disordered Mn vacancies and competing magnetic interactions in the [Mn1 - xT layers. The Zn analog also has charge density wave order at room temperature with a similar q-vector having the c* component similar to 0.346 confirmed by selected-area electron diffraction. Electron transfer from [KM1 - xT to [LaTe layers exists in KLaM1 (-) Te-x(4), leading to an enhanced electronic specific heat coefficient. The resistivities of KLaM1 - xTe4 (M = Mn and Zn) exhibit metallic behavior at high temperatures and an upturn at low temperatures, suggesting partial localization of carriers in the [LaTe layers with some degree of disorder associated with the M atom vacancies in the [M1 - xT layers.



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