1/f noise in the quasi-two-dimensional organic conductor {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl.
Resistance noise spectroscopy is applied to bulk single crystals of the quasi-two-dimensional organic conductor {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl both under moderate-pressure and at ambient-pressure conditions. When pressurized, the system can be shifted to the inhomogeneous coexistence region of antiferromagnetic insulating and superconducting phases, where percolation effects dominate the electronic fluctuations [J. Moeller et al., Phys. Rev. Lett. 102, 047004 (2009)]. Independent of the pressure conditions, at higher temperatures we observe generic 1/f{alpha}-type spectra, typical for this class of quasi-two-dimensional organic charge-transfer salts. The magnitude of the electronic noise is extremely enhanced compared to typical values of homogeneous semiconductors or metals. This indicates that a highly inhomogeneous current distribution may be an intrinsic property of organic charge-transfer salts. The temperature dependence of the nearly 1/f spectra can be very well described by a generalized random fluctuation model [P. Dutta, P. Dimon, and P. M. Horn, Rev. Lett. 43, 646 (1979)]. We find that the number of fluctuators and/or their coupling to the electrical resistance depend on the temperature. The phenomenological model explains a pronounced peak structure in the low-frequency noise at around 100 K, which is not observed in the resistivity itself, in terms of the thermally activated conformational degrees of freedom of the BEDT-TTF molecules ethylene endgroups.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); German Research Foundation (DFG)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 962073
- Report Number(s):
- ANL/MSD/JA-64700; TRN: US200919%%375
- Journal Information:
- Phys. Rev. B, Vol. 79, Issue 2009; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- ENGLISH
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