Uniaxial-Strain-Orientation Dependence of the Competition between Mott and Charge Ordered Phases and their Corresponding Superconductivity of beta -(BDA-TTP) sub( 2)I sub( 3)

• Published in: Journal of the Physical Society of Japan 2012-12, Vol.81 (12), p.1-1
• Main Authors: Nuruzzaman, Md, Yokogawa, Keiichi, Yoshino, Harukazu, Yoshimoto, Haruo, Kikuchi, Koichi, Kaihatsu, Takayuki, Yamada, Jun-ichi, Murata, Keizo
• Format: Article
• Language: English
• Subjects: Charge; Charge transfer; Compressing; Electronics; Hydrostatic pressure; Phases; Strain; Superconductivity; Symbols
• ISSN: 0031-9015; 1347-4073

We studied the electronic transport properties of the charge transfer salt beta -(BDA-TTP) ... I ... [BDA-TTP: 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene] by applying uniaxial strains along the three crystallographic axes, and obtained three corresponding temperature-pressure phase diagrams. Three phase diagrams were quite dependent on the direction of compression. Following the preceding paper by Kikuchi et al. , we speculate that the insulating states are of 1/2-filled Mott insulators for the a - and b -axes compressions, and of 1/4-filled charge ordered states for the c -axis compression as well as hydrostatic pressure. The superconducting phase under uniaxial strain was realized with T ... = 5 K at 1.9 GPa along the a -axis and with T ... = 5.6 K at 1.75 GPa along the b -axis. Superconductivity was also reproduced with a T ... of 9.5 K at 1.0 GPa for the c -axis compressions in the range of 0.85 to 1.53 GPa as previously reported. We studied tentative measurement on upper critical fields, B ... 's of these superconductivities and found that the extrapolated values, B ... (0)'s, exceeded Pauli-limit by about 2-3 times. However, at least in terms of B ... , the difference in superconductivity associated with two different insulating states was not clear. (ProQuest: ... denotes formulae/symbols omitted.)