CYCLOTRON-RESONANCE IN THE ORGANIC CONDUCTOR (BEDO-TTF)(2)REO4(H2O) IN THE MILLIMETER WAVELENGTH BAND

Resonant microwave absorption in a (BEDO-TTF)(2)ReO4(H2O) organic cond uctor single crystal at a temperature of 1.9 K, a magnetic field of up to 70 kOe, and in the frequency band between 30 and 120 GHz has been studied. A spectral component due to the cyclotron resonance (CR) of t wo-dimensional charge carriers has been identified for nu greater than or equal to 80 GHz and H greater than or equal to 10 kOe. The effecti ve mass m(omega) increases with the frequency from m approximate to 0. 8 m(0) at nu = 80 GHz to m approximate to 0.95 m(0) at nu = 120 GHz. M easurements of the CR line position and FWHM as functions of frequency yield an independently determined imaginary part of the memory functi on M(omega), which controls the dynamic magnetoconductivity, and the r elaxation time tau(nu = 100 GHz) approximate to 2.9 x 10(-11) s, which is more than thirty times the value of this parameter in the low-freq uency limit tau(nu --> 0). The anomalous behavior of the CR line posit ion and FWHM is caused try the dispersion of both real and imaginary p arts of M(omega), which are probably due to strong Fermi-liquid effect s. (C) 1997 American Institute of Physics.