Electric field effect on magnetoresistance angular effects: New tool to study mass renormalization in quasi-one-dimensional organic conductors

We discuss a novel experimental method to study mass renormalization in quasi-one-dimensional (Q1D) conductors having open sheet-like Fermi surfaces. It is well known that the detailed shape of the sheet-like Fermi surface could be studied by using magetoresistance angular effects, which appear on the interlayer magnetoresistance as a function of magnetic field orientations. We have taken notice of the effect of additional electric fields on the magnetoresistance angular effects. The basic concept is as the followings. In the Q1D system, the interlayer electric field can be replaced with the effective magnetic field, which gives the same Lorentz force to an electron, for each Fermi sheet. So, the angular effects due to different Fermi sheets must show different shifts under electric fields. From this shift, we can directly estimate the Fermi velocity and/or the electron mass in the Q1D conductors. We have numerically checked this electric field effect, and have also experimentally confirmed the electric field effect in organic conductors (TMTSF)₂ClO₄ and α-(BEDT-TTF)₂KHg(SCN)₄, which have Q1D electron systems at low temperatures.