Magnetic responses of randomly depleted spin ladders

Abstract

The magnetic responses of a spin-1/2 ladder doped with non-magnetic impurities are studied using various methods and including the regime where frustration induces incommensurability. Several improvements are made on the results of the seminal work of Sigrist and Furusaki [J. Phys. Soc. Jpn. 65, 2385 (1996)]. Deviations from the Brillouin magnetic curve due to interactions are also analyzed. First, the magnetic profile around a single impurity and effective interactions between impurities are analyzed within the bond-operator mean-field theory and compared to density-matrix renormalization group calculations. Then, the temperature behavior of the Curie constant is studied in details. At zero-temperature, we give doping-dependent corrections to the results of Sigrist and Furusaki on general bipartite lattice and compute exactly the distribution of ladder cluster due to chain breaking effects. Using exact diagonalization and quantum Monte-Carlo methods on the effective model, the temperature dependence of the Curie constant is compared to a random dimer model and a real-space renormalization group scenario. Next, the low-part of the magnetic curve corresponding to the contribution of impurities is computed using exact diagonalization. The random dimer model is shown to capture the bulk of the curve, accounting for the deviation from the Brillouin response. At zero-temperature, the effective model prediction agrees relatively well with density-matrix renormalization group calculations. Finite-temperature effects are displayed within the effective model and for large depleted ladder models using quantum Monte-Carlo simulations. In all, the effect of incommensurability does not display a strong qualitative effect on both the magnetic susceptibility and the magnetic curve. Consequences for experiments on the BiCu2PO6 compound and other spin-gapped materials are briefly discussed.

24 pages, 20 figures

References in corpus (14)

• Anderson Transitions
• Bose-Einstein Condensation in Magnetic Insulators
• Controlling Luttinger liquid physics in spin ladders under a magnetic field
• Thermodynamics of the Spin Luttinger-Liquid in a Model Ladder Material
• Low temperature magnetization of the S=1/2 kagome antiferromagnet ZnCu_3(OH)_6Cl_2
• Field-Controlled Magnetic Order in the Quantum Spin-Ladder System (Hpip)2CuBr4
• Bridging frustrated-spin-chain and spin-ladder physics: quasi-one-dimensional magnetism of BiCu2PO6
• Chain breaks and the susceptibility of Sr_2Cu_{1-x}Pd_xO_{3+δ} and other doped quasi one-dimensional antiferromagnets
• Direct observation of impurity-induced magnetism in an S = 1/2 antiferromagnetic Heisenberg 2-leg spin ladder
• Phase diagrams and universality classes of random antiferromagnetic spin ladders
• Localization of spinons in random Majumdar-Ghosh chains
• Magnetic Bose glass phases of coupled antiferromagnetic dimers with site dilution
• Frustration effect on magnetic excitations in a two-leg spin-ladder system
• Bond-impurity induced bound states in disordered spin-1/2 ladders

Cited by in corpus (8)

• Entanglement properties of correlated random spin chains and similarities with conformal invariant systems
• Emergent interacting spin islands in a depleted strong-leg Heisenberg ladder
• Disorder-induced Revival of the Bose-Einstein Condensation in Ni(Cl${}_{1-x}$Br${}_x$)${}_2$-4SC(NH${}_2$)${}_2$ at High Magnetic Fields
• The tunable quantum spin ladder Cu(Qnx)(Cl${}_{(1-x)}$Br${}_x$)${}_2$
• Thermal Properties of Rung Disordered Two-leg Quantum Spin Ladders: Quantum Monte Carlo Study
• LT-scaling in depleted quantum spin ladders
• Momentum Signatures of Site Percolation in Disordered 2D Ferromagnets
• Spin-Spin Correlation Enhanced by Impurities in a Frustrated Two-leg Spin Ladder