Dimensionality-Mediated Semimetal-Semiconductor Transition in Ultrathin PtTe₂ Films

Meng-Kai Lin^1,2, Rovi Angelo B. Villaos^3*, Joseph A. Hlevyack^1,2, Peng Chen^1,2,4,5, Ro-Ya Liu^1,2,4,6, Chia-Hsiu Hsu³, Jose Avila⁷, Sung-Kwan Mo⁴, Feng-Chuan Chuang³, T.-C. Chiang^1,2

¹Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
²Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
³Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan
⁴Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA
⁵Shanghai Center for Complex Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
⁶Institute of Physics, Academia Sinica, Taipei, Taiwan
⁷Synchrotron SOLEIL and Universite Paris-Saclay, L’Orme des Merisiers, Saint-Aubin, France

* Presenter:Rovi Angelo B. Villaos, email:villaosrovi@g-mail.nsysu.edu.tw

Platinum ditelluride (PtTe₂), a type-II Dirac semimetal, remains semimetallic in ultrathin films down to just two triatomic layers (TLs) with a negative gap of −0.36 eV. Further reduction of the film thickness to a single TL induces a Lifshitz electronic transition to a semiconductor with a large positive gap of +0.79 eV. This transition is evidenced by experimental band structure mapping of films prepared by layer-resolved molecular beam epitaxy, and by comparing the data to first-principles calculations using a hybrid functional. The results demonstrate a novel electronic transition at the two-dimensional limit through film thickness control.

Keywords: Transition metal dichalcogenides, Platinum ditelluride, ultrathin film, ARPES, Density Functional Theory