Excitations and Quantum Fluctuations in Site Diluted Two-Dimensional Antiferromagnets

Abstract

We study the effect of site dilution and quantum fluctuations in an antiferromagnetic spin system on a square lattice within the linear spin-wave approximation. By performing numerical diagonalization in real space and finite-size scaling, we characterize the nature of the low-energy spin excitations for different dilution fractions up to the classical percolation threshold. We find nontrivial signatures of fractonlike excitations at high frequencies. Our simulations also confirm the existence of an upper bound for the amount of quantum fluctuations in the ground state of the system, leading to the persistence of long-range order up to the percolation threshold. This result is in agreement with recent neutron-scattering experimental data and quantum Monte Carlo numerical calculations. We also show that the absence of a quantum critical point below the classical percolation threshold holds for a large class of systems whose Hamiltonians can be mapped onto a system of coupled noninteracting massless bosons.

RevTex 4, 16 pages, 8 EPS figures, typos corrected, data from Ref. 9 added, few minor changes in the text, to appear in Phys. Rev. B

References in corpus (11)

• Novel Symmetry Classes in Mesoscopic Normal-Superconducting Hybrid Structures
• Metallic behavior and related phenomena in two dimensions
• Efficient Monte Carlo algorithm and high-precision results for percolation
• Bosonic Excitations in Random Media
• Quantum Impurities in the Two-Dimensional Spin One-Half Heisenberg Antiferromagnet
• Classical percolation transition in the diluted two-dimensional S=1/2 Heisenberg antiferromagnet
• Diluted quantum antiferromagnets: spin excitations and long-range order
• Some generic aspects of bosonic excitations in disordered systems
• Multi-critical point in a diluted bilayer Heisenberg quantum antiferromagnet
• Quantum vs. Geometric Disorder in a Two-Dimensional Heisenberg Antiferromagnet
• Neutron Scattering, Magnetometry, and Quantum Monte Carlo Study of the Randomly-Diluted Spin-1/2 Square-Lattice Heisenberg Antiferromagnet

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• Site Dilution in the Half-Filled One-Band Hubbard Model: Ring Exchange, Charge Fluctuations and Application to La2Cu_{1-x}(Mg/Zn)_xO4
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• Impurity-induced frustration: low-energy model of diluted oxides
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• Theoretical Analysis of the Reduction of Neel Temperature in La${}_2$(Cu${}_{1-x}$Zn(or Mg)${}_x)$O${}_4$
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