Thermopower study of (TMTSF)_2AsF_6 SDW state

摘要

The thermoelectric power of (TMTSF)_2AsF_6was measured along the a-axis. A thermal hysteresis was found inthe SDW state. Effects of magnetic fields were investigated for thefield direction parallel to the a-, b'- and c*-axes, where b' isdefined as being perpendicular to both the a- and c*-axes. Therewas no magnetic hysteresis nor magnetic field influence on thethermal hysteresis. Suggestion is made about random pinning ofSDW or structural changes accompanying SDW transition or bothbeing origin of this phenomenon. The temperature and magneticfield dependece of the thermopower suggests the presence ofsubphases of SDW divided by T_1=2K and T_2=4.5K.