Stress-induced metal-to-nonmetal transition in the quasi-one-dimensional superconductorTl2Mo6

Abstract

We report a study of the effect of uniaxial stress on the electrical properties of T12Mo6Se6. Stress suppresses the superconducting transition temperature and induces a metal-to-nonmetal phase transition. Nonlinear I-V characteristics and broadband noise measurements in the semiconducting phase suggest that the transition may be due to the formation of a charge-density or spin-density wave. A transition temperature T~= 15+3 K and energy gap Eg =57 K are deduced from resistance measurements in the nonmetallic state.

Emergent Superconductivity in Low Dimensions

“…A few works in the 1980s and 1990s attempted to explain the MI transitions observed in the M 2 _ 0 Mo6Se6 family [74,76,77,85]. These studies took into account early bandstructure calculations predicting 3 contributions to the Fermi surfaces (one Mo d band and two 3D electron pockets at the zone boundary).…”

A device for the application of uniaxial strain to single crystal samples for use in synchrotron radiation experiments

“…The molybdenum selenides with group 3 A (Tl or In) guest ions become superconducting at temperatures of 3-6.5 K and 2.9 K respectively, while those with group 1 A guest ions exhibit a temperature-dependent metal-to-insulator crossover. 16 Tl 2 Mo 6 Se 6 displays metallic behaviour down to low temperature, but has been driven into a high resistance state by the application of uniaxial strain, 8 which may result weakly coupled by the guest ions M, which occupy the channels between the chains. 17 Mo 6 Se 6 nanowires have been predicted to exhibit high breaking strains of greater than 8.2%.…”

“…Using E = 400 GPa for Mo 6 Se 6 nanowires, 8 we estimate k sample = 13 ± 8 N µm −1 . A slightly higher value for the Mo 6 Se 6 Young's modulus of 570 GPa has been calculated elsewhere in the literature, 18 but the uncertainty in E is small compared to that in A and l. This sample stiffness is likely to be an overestimate, since we have assumed a perfectly homogeneous crystalline sample.…”

“…Mechanical methods are able to provide dynamic strain without the requirement of a transmitting medium. [7][8][9] Dynamic rather than static strain is desirable as it offers the ability to continuously tune a material through distinct quantum ground states. 8,10 Modern synchrotron techniques provide an ideal probe to observe and measure the continuous perturbation to the electronic and structural properties that tunable strain provides.…”

“…[7][8][9] Dynamic rather than static strain is desirable as it offers the ability to continuously tune a material through distinct quantum ground states. 8,10 Modern synchrotron techniques provide an ideal probe to observe and measure the continuous perturbation to the electronic and structural properties that tunable strain provides. When both optical access and dynamic strain are required, hydrostatic pressure and epitaxial growth are generally unsuitable due to the reasons discussed above and hence a mechanical device becomes essential.…”