Suppression of both superconductivity and structural transition in hole-doped MoTe2 induced by Ta substitution

Type-II Weyl semimetal MoTe2 exhibits a first-order structural transition at T-s similar to 250 K and superconducts at T-c similar to 0.1 K at ambient pressure. Both T-s and T-c can be manipulated by several tuning parameters, such as hydrostatic pressure and chemical substitution. It is often reported that suppressing T-s enhances T-c, but our study shows a different behavior when MoTe2 is hole-doped by Ta. When T-s is suppressed by Ta doping, T-c is also suppressed. Our findings suggest that the suppression of T-s does not necessarily enhance superconductivity in MoTe2. By connecting with the findings of electron-doped MoTe2, we argue that varying electron carrier concentration can effectively tune T-c. In addition, the Hall coefficient is enhanced around the doping region, where T-s is completely suppressed, suggesting that the critical scattering around the structural transition may also play a role in suppressing T-c.