One-dimensional hopping conductivity of the spin-ladder CaCu2O3 single crystals

Abstract

Resistivity, ρ, of the spin-ladder compound CaCu2O3 is investigated between T ~ 130− 450 K. The ρ (T) data exhibit an activated dependence characterized by a nearest-neighbor hopping followed by a variable-range hopping (VRH) regime when T is decreased. The observed VRH conductivity on the low-temperature interval obeys the law ln ρ ~ T −3/4 . This law can be explained and the correct matching of the characteristic energy and length scales can be found by treating CaCu2O3 as a three-dimensional array of quasi-one-dimensional electron crystals.