Bandgap opening in MoTe2 thin flakes induced by surface oxidation

Gan，Yuan1,2; Liang，Jiyuan2; Cho，Chang woo2; Li，Si3,4; Guo，Yanping2; Ma，Xiaoming2,5; Wu，Xuefeng2; Wen，Jinsheng1; Du，Xu6; He，Mingquan7; Liu，Chang2; Yang，Shengyuan A.4; Wang，Kedong2; Zhang，Liyuan2

2020-06-01

10.1007/s11467-020-0952-x

Frontiers of Physics   Impact Factor & Quartile

2095-0462

2095-0470

Recently, the layered transition metal dichalcogenide 1T′-MoTe has generated considerable interest due to their superconducting and non-trivial topological properties. Here, we present a systematic study on 1T′-MoTe single-crystal and exfoliated thin-flakes by means of electrical transport, scanning tunnelling microscope (STM) measurements and band structure calculations. For a bulk sample, it exhibits large magneto-resistance (MR) and Shubnikov–de Hass oscillations in ρxx and a series of Hall plateaus in ρxy at low temperatures. Meanwhile, the MoTe thin films were intensively investigated with thickness dependence. For samples, without encapsulation, an apparent transition from the intrinsic metallic to insulating state is observed by reducing thickness. In such thin films, we also observed a suppression of the MR and weak anti-localization (WAL) effects. We attributed these effects to disorders originated from the extrinsic surface chemical reaction, which is consistent with the density functional theory (DFT) calculations and in-situ STM results. In contrast to samples without encapsulated protection, we discovered an interesting superconducting transition for those samples with hexagonal Boron Nitride (h-BN) film protection. Our results indicate that the metallic or superconducting behavior is its intrinsic state, and the insulating behavior is likely caused by surface oxidation in few layer 1T’-MoTe flakes.

layered transition metal dichalcogenides (TMDs) metal-insulator transition surface oxidation two-dimensional materials

SCI

English

Corresponding

WOS:000519012500002

2-s2.0-85082324478

Scopus

1.National Laboratory of Solid State Microstructures and Department of Physics,Nanjing University,Nanjing,210093,China
2.Department of Physics,Southern University of Science and Technology,Shenzhen,518055,China
3.School of Physics and Electronics,Hunan Normal University,Changsha,410081,China
4.Research Laboratory for Quantum Materials,Singapore University of Technology and Design,Singapore,487372,Singapore
5.Beijing National Laboratory for Condensed Matter Physics and Institute of Physics,Chinese Academy of Sciences,Beijing,100190,China
6.Department of Physics and Astronomy,Stony Brook University,Stony Brook,11794,United States
7.Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart Materials,College of Physics,Chongqing University,Chongqing,401331,China

Gan，Yuan,Liang，Jiyuan,Cho，Chang woo,et al. Bandgap opening in MoTe2 thin flakes induced by surface oxidation[J]. Frontiers of Physics,2020,15(3).

Gan，Yuan.,Liang，Jiyuan.,Cho，Chang woo.,Li，Si.,Guo，Yanping.,...&Zhang，Liyuan.(2020).Bandgap opening in MoTe2 thin flakes induced by surface oxidation.Frontiers of Physics,15(3).

Gan，Yuan,et al."Bandgap opening in MoTe2 thin flakes induced by surface oxidation".Frontiers of Physics 15.3(2020).