Current-Density Dependence of the Charge-Ordering Gap in the Organic Salt θ-(BEDT-TTF)_2CsM(SCN)_4 (M=Zn, Co, and Co_<0.7>Zn_<0.3>)(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

概要

論文の詳細を見る
We have measured and analyzed the resistivity and voltage-current characteristics of the chargeordered organic salt θ-(BEDT-TTF)_2CsM(SCN)_4 (M=Zn, Co, and Co_<0.7>Zn_<0.3>). At 4.3K, all the samples show giant nonlinear conduction, in which the c-axis resistivity markedly decreases with external current by a factor of 10 against a small electric field of 1V/cm. The temperature dependence of the resistivity is well described by an activation law, the activation energy of which is evaluated to be 2meV in the lowcurrent limit, and linearly decreases with external current. The activation energy and x-ray intensity near q_2=(0,k,1/2) are found to show the same dependence on current density. This coincidence strongly suggests that the energy gap of the charge order indexed by q_2 is an order parameter of this phenomenon.
社団法人日本物理学会の論文
2009-02-15