A Novel <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow> <msqrt><mrow><mn>19</mn></mrow> </msqrt> </mrow> <annotation>$\sqrt {19} $</annotation></semantics> </math> × <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow> <msqrt><mrow><mn>19</mn></mrow> </msqrt> </mrow> <annotation>$\sqrt {19} $</annotation></semantics> </math> Superstructure in Epitaxially Grown 1T-TaTe<sub>2</sub>.

Hwang, Jinwoong; Jin, Yeongrok; Zhang, Canxun; Zhu, Tiancong; Kim, Kyoo; Zhong, Yong; Lee, Ji-Eun; Shen, Zongqi et al. · Adv Mater · 2022

basic_science · Level V

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Abstract

The spontaneous formation of electronic orders is a crucial element for understanding complex quantum states and engineering heterostructures in 2D materials. A novel <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow> <msqrt><mrow><mn>19</mn></mrow> </msqrt> </mrow> <annotation>$\sqrt {19} $</annotation></semantics> </math> × <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow> <msqrt><mrow><mn>19</mn></mrow> </msqrt> </mrow> <annotation>$\sqrt {19} $</annotation></semantics> </math> charge order in few-layer-thick 1T-TaTe<sub>2</sub> transition metal dichalcogenide films grown by molecular beam epitaxy, which has not been realized, is report. The photoemission and scanning probe measurements demonstrate that monolayer 1T-TaTe<sub>2</sub> exhibits a variety of metastable charge density wave orders, including the <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow> <msqrt><mrow><mn>19</mn></mrow> </msqrt> </mrow> <annotation>$\sqrt {19} $</annotation></semantics> </math> × <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow> <msqrt><mrow><mn>19</mn></mrow> </msqrt> </mrow> <annotation>$\sqrt {19} $</annotation></semantics> </math> superstructure, which can be selectively stabilized by controlling the post-growth annealing temperature. Moreover, it is found that only the <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow> <msqrt><mrow><mn>19</mn></mrow> </msqrt> </mrow> <annotation>$\sqrt {19} $</annotation></semantics> </math> × <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow> <msqrt><mrow><mn>19</mn></mrow> </msqrt> </mrow> <annotation>$\sqrt {19} $</annotation></semantics> </math> order persists in 1T-TaTe<sub>2</sub> films thicker than a monolayer, up to 8 layers. The findings identify the previously unrealized novel electronic order in a much-studied transition metal dichalcogenide and provide a viable route to control it within the epitaxial growth process.