Thermomechanical Manipulation of Electric Transport in MoTe₂

Abstract

Layered semimetals such as monoclinic MoTe2 and WTe2 demonstrate superconducting, topological insulating, and Weyl semimetallic states based on their unique electronic band topology. While doping concentration, lattice constants, and spin–orbit coupling can largely modulate the quantum states of the semimetals, a puzzling issue is that their functional carrier density and magnetoresistance for practical applications critically vary by temperature, which cannot be explained by the conventional phonon effect or a structural phase transition. Here, a native doping‐mediated thermomechanical manipulation of electric transport in semimetallic MoTe2 is reported, where effective transport is controlled by temperature in an equivalent manner to electric gating. Combining X‐ray diffraction, scanning tunneling microscopy, transport measurements, and first‐principles calculations, a Fermi level shift and subsequent changes in electronic structures are revealed as the origins of the practical transport changes in MoTe2. Moreover, the initial doping state of the MoTe2, determined by the Te vacancy density in two different growth methods, reciprocally affects the thermomechanical lattice and band structure changes, which is promising for novel electronic applications such as magnetic sensors and memory devices with layered semimetals.

Phase Engineering of 2D Materials

“…Temperature alters the stacking order of TMDs. It has been reported that orthorhombic (T d ) and monoclinic (1T′) phases can be observed in MoTe 2 at different temperatures . Cheon et al reported that the 1T′ and T d phases have strong in-plane anisotropy in the interlayer coupling.…”

“…It has been reported that orthorhombic (T d ) and monoclinic (1T′) phases can be observed in MoTe 2 at different temperatures. 110 Cheon et al reported that the 1T′ and T d phases have strong in-plane anisotropy in the interlayer coupling. Thus, the energy required to slip the layer is small, 111 leading to such a unique stacking order transition.…”

A Polymorphic Memtransistor with Tunable Metallic and Semiconducting Channel

“…We explain the shift in critical V LG by the generation of Te vacancies during the liquid ionic gating, which induces electron doping. [ 32 ] Moreover, we can use a certain condition of liquid ionic gating to electrochemically etch the device channel (Figure S15, Supporting Information), further decreasing the critical V LG for phase transition.…”

Promoted Electronic Coupling of Acoustic Phonon Modes in Doped Semimetallic MoTe2

“…The native Tevacancy in semimetallic MoTe 2 is responsible for a temperature-manipulated transport in a manner equivalent to electrical gating. 34 Through precisely generating Te-vacancies with inducing electron-doping, the T d -MoTe 2−x samples show a promoted superconducting transition at 2.1 K compared with stoichiometric samples (no superconducting state down to 10 mK). 35 Also, the charge doping can modulate structural stability and induce phase transitions for layered MoTe 2 .…”

“…The lattice distortion associated with the difference in the atomic radius may also play some role in activating the EPC through exerting the strain. The native Te-vacancy in semimetallic MoTe 2 is responsible for a temperature-manipulated transport in a manner equivalent to electrical gating . Through precisely generating Te-vacancies with inducing electron-doping, the T d -MoTe 2– x samples show a promoted superconducting transition at 2.1 K compared with stoichiometric samples (no superconducting state down to 10 mK) .…”