We study the transport of electrons through a long quantum wire connecting two bulk leads. As the electron density in the wire is lowered, the Coulomb interactions lead to short-range crystalline ordering of electrons. In this Wigner crystal state the spins of electrons form an antiferromagnetic Heisenberg spin chain with exponentially small exchange coupling $J$. Inhomogeneity of the electron density due to the coupling of the wire to the leads results in violation of spin-charge separation in the device. As a result the spins affect the conductance of the wire. At zero temperature the low-energy spin excitations propagate freely through the wire, and its conductance remains $2e^2∕h$. Since the energy of the elementary excitations in the spin chain (spinons) cannot exceed $\pi J∕2$, the conductance of the wire acquires an exponentially small negative correction $\delta G\propto -\exp (-\pi J∕2T)$ at low temperatures $T⪡J$. At higher temperatures, $T⪢J$, most of the spin excitations in the leads are reflected by the wire, and the conductance levels off at a new universal value $e^2∕h$.

• Received 23 May 2004

DOI:https://doi.org/10.1103/PhysRevB.70.245319