Field-dependent spin and heat conductivities of dimerized spin-1/2 chains

Abstract

We study the spin and heat conductivity of dimerized spin-1/2 chains in homogeneous magnetic fields at finite temperatures. At zero temperature, the model undergoes two field-induced quantum phase transitions from a dimerized, into a Luttinger, and finally into a fully polarized phase. We search for signatures of these transitions in the spin and heat conductivities. Using exact diagonalization, we calculate the Drude weights, the frequency dependence of the conductivities, and the corresponding integrated spectral weights. As a main result, we demonstrate that both the spin and heat conductivity are enhanced in the gapless phase and most notably at low frequencies. In the case of the thermal conductivity, however, the field-induced increase seen in the bare transport coefficients is suppressed by magnetothermal effects, caused by the coupling of the heat and spin current in finite magnetic fields. Our results complement recent magnetic transport experiments on spin ladder materials with sufficiently small exchange couplings allowing access to the field-induced transitions.

10 pages, Revtex4, 17 figures

References in corpus (21)

• Controlling Luttinger liquid physics in spin ladders under a magnetic field
• Thermodynamics of the Spin Luttinger-Liquid in a Model Ladder Material
• Heat conduction in low-dimensional quantum magnets
• Thermal conductivity via magnetic excitations in spin-chain materials
• A real-time study of diffusive and ballistic transport in spin-1/2 chains using the adaptive time-dependent density matrix renormalization group method
• Field-Controlled Magnetic Order in the Quantum Spin-Ladder System (Hpip)2CuBr4
• Magnetothermal transport in the spin-1/2 chains of copper pyrazine dinitrate
• Transport in open spin chains: A Monte Carlo wave-function approach
• Spin conductivity in almost integrable spin chains
• Thermal transport in one-dimensional spin gap systems
• Thermal transport of the XXZ chain in a magnetic field
• Negative differential conductivity in far-from-equilibrium quantum spin chains
• Diverging thermal expansion of the spin-ladder system (C${}_5$H${}_{12}$N)${}_2$CuBr${}_4$
• Field-dependent thermal transport in the Haldane chain compound NENP
• Control of heat transport in quantum spin systems
• Magnon Heat Conductivity and Mean Free Paths in Two-Leg Spin Ladders: A Model-Independent Determination
• Finite Drude weight for 1D low temperature conductors
• Comment on "Anomalous Thermal Conductivity of Frustrated Heisenberg Spin Chains and Ladders"
• Spin-spin correlations of the spin-ladder compound (C${}_5$H${}_{12}$N)${}_2$CuBr${}_4$ measured by magnetostriction and comparison to Quantum Monte Carlo results
• Heat transport of clean spin-ladders coupled to phonons: Umklapp scattering and drag
• Equivalence of transport coefficients in bath-induced and dynamical scenarios