## Abstract

The charge transport in polydiacetylene quasi-1D single crystals (PDA-PTS) has been studied as a function of temperature, electric and magnetic fields. In the Ohmic regime the temperature dependence of the resistivity, ρ(T), is characteristic of hopping conduction with a crossover at T<50 K from activated ρ(T) =ρ_{0} exp [(E_{A}/k_{B}T)], with E_{A}∼13-19 meV to variable-range hopping transport ρ(T)=ρ_{0} exp [(T_{0}/T)^{p}], with p∼0.65-0.70. At modest electric fields the resistivity depends as ρ(E,T)=ρ(0,T)exp (-eEL/k_{B}T), where the characteristic hopping length changes as L∼T^{-m} with m∼0.5 at T>50 K and m∼0.75 at T<50 K. At high electric fields the low temperature current becomes temperature independent and follows: I(E) =I_{0} exp [-(E _{/0}E)^{0.5}], which corresponds to the regime of activation-free phonon-emission-assisted hopping conduction. Magnetoresistance at T<4.2 K is negative and depends on magnetic fields H as In[ρ(H,T)/ρ(0,T)]∼H^{0.5}. The results demonstrate that at low temperature the charge transport is mainly supported due to quasi-1D variable-range hopping with the influence of Coulomb interactions. At higher temperatures the thermally activated nearest-neighbor transport by small polarons is dominant.

Original language | English |
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Article number | 214203 |

Pages (from-to) | 214203-1-214203-6 |

Journal | Physical Review B - Condensed Matter and Materials Physics |

Volume | 69 |

Issue number | 21 |

DOIs | |

State | Published - Jun 2004 |