Control of electronic properties ofα−(BEDT−TTF)

Abstract

Systematic uniaxial strain studies of ␣-͑BEDT-TTF͒ 2 M Hg͑SCN͒ 4 (M ϭK,NH 4 ͒ have been carried out. By controlling the in-plane lattice parameters a and c independently, we find that both compounds have essentially the same phase diagram in electronic properties, although, under the hydrostatic pressures, they show quite different phase diagrams. The K salt shows the superconductivity like NH 4 salt under the c-axis uniaxial strain, and the latter undergoes a transition to the density-wave state like the former under the a-axis uniaxial strain. These changes in electronic structures are verified by measuring the angle-dependent magnetoresistance. The electronic properties of these compounds can be systematically understood as a function of c/a, the ratio of the in-plane lattice parameters.

Density-wave instability inα−(BEDT-TTF)2KHg(SCN)4Foury-Leylekian1, Pouget2, Lee3 et al. 2010Phys. Rev. B273340View full textAdd to dashboardCite

“…Consistently, it is found that minor external constraints suppress the CDW transitions. Under pressure, the bump anomaly in resistivity announcing the CDW ground state is completely suppressed above 2.5 Kbars, 76 and the restored metallic state undergoes a transition toward a superconducting state at ϳ0.1 K. 77 The CDW is also suppressed under uniaxial strain 78 or uniaxial stress. 79,80 For uniaxial strain applied along b ‫ء‬ or c and uniaxial stress applied along a or b ‫ء‬ superconductivity has been detected below ϳ1-2 K.…”

C13NMR study of the charge-ordered state near the superconducting transition in the organic superconductorβ′′−(BEDT-T

“…Charge instability is also observed in quasi-two-dimensional organic conductors (BEDT-TTF) 2 X [bis(ethylenedithio)-tetrathiafulvalene] salts. In some BEDT-TTF salts, superconductivity appears directly after the suppression of the CO transition by applying chemical or mechanical pressure [10][11][12]. However, the CO transition temperature is much higher than the SC transition temperature T c [13,14], and the two phenomena thus appear * yihara@phys.sci.hokudai.ac.jp unrelated.…”

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

“…551 Along the a-axis, however, T c decreases monotonically as an applied pressure increases up to 0.6 GPa, above which the superconductivity eventually disappears. A resistivity hump analogous to that observed in -(ET) 2 KHg(SCN) 4 appears below ca.…”