Hiroshi Tokumoto

Spin-density-wave and superconducting states in thermally quenched (TMTSF)2ClO4

Abstract Successive transitions from metal to the spin-density-wave (SDW) state and the three-dimensional superconducting (3D-SC) state were found in thermally quenched bis-tetramethyltetraselenafulvalenium perchlorate, (TMTSF)2ClO4. The SDW state was suppressed after the sample was warmed above ∼25 K and cooled slowly. The appearance of the SDW state in addition to the 3D-SC state in the quenched sample is interpreted by the decrease in interchain coupling which could result from the thermal quenching of a high temperature configuration with disordered (ClO4)-anions. The effect of thermal quenching on quantum oscillations in transverse magnetoresistance was also studied.

Kink Deformation of (TMTSF)2ClO4 Single Crystal and Its Influence on Electrical Resistivity

Mechanical kinks are formed in a needle crystal of bis (tetramethyltetraselenafulvalenium) perchlorate, (TMTSF) 2 ClO 4 , by applying stresses. The kink which has definite angle of 18.4° accompanies antikink with the same angle in the opposite direction. By the X-ray precession photograph, we show that the kink is ascribed to the mechanical twinning with the boundary on the (210) plane. The electrical resistivity measurements in a deformed part lying between the kink and antikink and in a region including the kink were carried out, but they did not show substantial difference compared with those in an underformed part. However, the kink which accompanies distortion in a molecular stack is considered to be one of causes of the resistance jump (stepwise increase in resistance), which is frequently observed during cooling.