Neutron scattering, magnetometry, and quantum Monte Carlo study of the randomly diluted spin-1/2 square-lattice Heisenberg antiferromagnet

O. P. Vajk; M. Greven; P. K. Mang; J. W. Lynn

doi:10.1016/S0038-1098(02)00708-1

Neutron scattering, magnetometry, and quantum Monte Carlo study of the randomly diluted spin-1/2 square-lattice Heisenberg antiferromagnet

O. P. Vajk, M. Greven, P. K. Mang, J. W. Lynn

Physics and Astronomy (Twin Cities)

Research output: Contribution to journal › Conference article › peer-review

15 Scopus citations

Abstract

We have successfully grown sizable single crystals of La₂Cu_1-z(Zn,Mg)_zO₄ with up to nearly half of the magnetic Cu sites replaced by non-magnetic Zn and Mg. Neutron scattering, SQUID magnetometry, and complementary quantum Monte Carlo (QMC) simulations demonstrate that this material is an excellent model system for the study of site percolation of the square-lattice Heisenberg antiferromagnet (SLHAF) in the quantum-spin limit S = 1/2. Carefully oxygen-reduced samples exhibit Néel order up to the percolation threshold for site dilution, z_p ≈ 40.7%. For z > 10%, the material exhibits a low-temperature tetragonal (LTT) structural phase, with a transition temperature that increases linearly with doping. Above z ≈ 25%, Néel order occurs in the LTT phase. Up to at least z = 35%, the Néel temperature T_N(z) of the experimental system corresponds to the temperature at which QMC indicates that the spin correlations for the nearest-neighbor S = 1/2 SLHAF have grown to approximately 100 lattice constants. Neutron scattering measurements of the static structure factor in the paramagnetic regime allow the determination of the two-dimensional spin correlations, which are found to be in excellent quantitative agreement with QMC over a wide common temperature and doping range. Neutron scattering and QMC results for the temperature dependence of the static structure factor amplitude S(π,π) are in good agreement as well. As the concentration of non-magnetic sites is increased, the magnetic correlation length ξ(T,z) crosses over from an exponential dependence on ρ_s/T to power-law behavior in the temperature regime studied. Fits to a heuristic cross-over form for ξ(T,z) allow an estimate of the spin stiffness, ρ_s = ρ_s(z), which approaches zero at z = z_p. The combined experimental and numerical data presented here provide valuable quantitative information for tests of theories of the randomly diluted S = 1/2 SLHAF.

Original language	English (US)
Pages (from-to)	93-101
Number of pages	9
Journal	Solid State Communications
Volume	126
Issue number	1-2
DOIs	https://doi.org/10.1016/S0038-1098(02)00708-1
State	Published - Apr 2003
Event	High-Tc Superconductivity Workshop - Williamsburg, VA, United States Duration: Jun 7 2002 → Jun 7 2002

Bibliographical note

Funding Information:
O.P.V. and M.G. thank A. Aharony, A.H. Castro Neto, A.L. Chernyshev, A.W. Sandvik, and E.F. Shender for helpful discussions. The work at Stanford was supported by the US Department of Energy under contract nos. DE-FG03-99ER45773 and DE-AC03-76SF00515, by NSF CAREER Award no. DMR9985067, and by the A. P. Sloan Foundation.

Keywords

A. Insulators
B. Crystal growth
D. Phase transitions
D. Spin dynamics
E. Neutron scattering

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10.1016/S0038-1098(02)00708-1

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@article{ed57f11f3c1742c3b36ada6608537209,

title = "Neutron scattering, magnetometry, and quantum Monte Carlo study of the randomly diluted spin-1/2 square-lattice Heisenberg antiferromagnet",

abstract = "We have successfully grown sizable single crystals of La2Cu1-z(Zn,Mg)zO4 with up to nearly half of the magnetic Cu sites replaced by non-magnetic Zn and Mg. Neutron scattering, SQUID magnetometry, and complementary quantum Monte Carlo (QMC) simulations demonstrate that this material is an excellent model system for the study of site percolation of the square-lattice Heisenberg antiferromagnet (SLHAF) in the quantum-spin limit S = 1/2. Carefully oxygen-reduced samples exhibit N{\'e}el order up to the percolation threshold for site dilution, zp ≈ 40.7%. For z > 10%, the material exhibits a low-temperature tetragonal (LTT) structural phase, with a transition temperature that increases linearly with doping. Above z ≈ 25%, N{\'e}el order occurs in the LTT phase. Up to at least z = 35%, the N{\'e}el temperature TN(z) of the experimental system corresponds to the temperature at which QMC indicates that the spin correlations for the nearest-neighbor S = 1/2 SLHAF have grown to approximately 100 lattice constants. Neutron scattering measurements of the static structure factor in the paramagnetic regime allow the determination of the two-dimensional spin correlations, which are found to be in excellent quantitative agreement with QMC over a wide common temperature and doping range. Neutron scattering and QMC results for the temperature dependence of the static structure factor amplitude S(π,π) are in good agreement as well. As the concentration of non-magnetic sites is increased, the magnetic correlation length ξ(T,z) crosses over from an exponential dependence on ρs/T to power-law behavior in the temperature regime studied. Fits to a heuristic cross-over form for ξ(T,z) allow an estimate of the spin stiffness, ρs = ρs(z), which approaches zero at z = zp. The combined experimental and numerical data presented here provide valuable quantitative information for tests of theories of the randomly diluted S = 1/2 SLHAF.",

keywords = "A. Insulators, B. Crystal growth, D. Phase transitions, D. Spin dynamics, E. Neutron scattering",

author = "Vajk, {O. P.} and M. Greven and Mang, {P. K.} and Lynn, {J. W.}",

note = "Funding Information: O.P.V. and M.G. thank A. Aharony, A.H. Castro Neto, A.L. Chernyshev, A.W. Sandvik, and E.F. Shender for helpful discussions. The work at Stanford was supported by the US Department of Energy under contract nos. DE-FG03-99ER45773 and DE-AC03-76SF00515, by NSF CAREER Award no. DMR9985067, and by the A. P. Sloan Foundation.; High-Tc Superconductivity Workshop ; Conference date: 07-06-2002 Through 07-06-2002",

year = "2003",

month = apr,

doi = "10.1016/S0038-1098(02)00708-1",

language = "English (US)",

volume = "126",

pages = "93--101",

journal = "Solid State Communications",

issn = "0038-1098",

publisher = "Elsevier Ltd",

number = "1-2",

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TY - JOUR

T1 - Neutron scattering, magnetometry, and quantum Monte Carlo study of the randomly diluted spin-1/2 square-lattice Heisenberg antiferromagnet

AU - Vajk, O. P.

AU - Greven, M.

AU - Mang, P. K.

AU - Lynn, J. W.

N1 - Funding Information: O.P.V. and M.G. thank A. Aharony, A.H. Castro Neto, A.L. Chernyshev, A.W. Sandvik, and E.F. Shender for helpful discussions. The work at Stanford was supported by the US Department of Energy under contract nos. DE-FG03-99ER45773 and DE-AC03-76SF00515, by NSF CAREER Award no. DMR9985067, and by the A. P. Sloan Foundation.

PY - 2003/4

Y1 - 2003/4

N2 - We have successfully grown sizable single crystals of La2Cu1-z(Zn,Mg)zO4 with up to nearly half of the magnetic Cu sites replaced by non-magnetic Zn and Mg. Neutron scattering, SQUID magnetometry, and complementary quantum Monte Carlo (QMC) simulations demonstrate that this material is an excellent model system for the study of site percolation of the square-lattice Heisenberg antiferromagnet (SLHAF) in the quantum-spin limit S = 1/2. Carefully oxygen-reduced samples exhibit Néel order up to the percolation threshold for site dilution, zp ≈ 40.7%. For z > 10%, the material exhibits a low-temperature tetragonal (LTT) structural phase, with a transition temperature that increases linearly with doping. Above z ≈ 25%, Néel order occurs in the LTT phase. Up to at least z = 35%, the Néel temperature TN(z) of the experimental system corresponds to the temperature at which QMC indicates that the spin correlations for the nearest-neighbor S = 1/2 SLHAF have grown to approximately 100 lattice constants. Neutron scattering measurements of the static structure factor in the paramagnetic regime allow the determination of the two-dimensional spin correlations, which are found to be in excellent quantitative agreement with QMC over a wide common temperature and doping range. Neutron scattering and QMC results for the temperature dependence of the static structure factor amplitude S(π,π) are in good agreement as well. As the concentration of non-magnetic sites is increased, the magnetic correlation length ξ(T,z) crosses over from an exponential dependence on ρs/T to power-law behavior in the temperature regime studied. Fits to a heuristic cross-over form for ξ(T,z) allow an estimate of the spin stiffness, ρs = ρs(z), which approaches zero at z = zp. The combined experimental and numerical data presented here provide valuable quantitative information for tests of theories of the randomly diluted S = 1/2 SLHAF.

AB - We have successfully grown sizable single crystals of La2Cu1-z(Zn,Mg)zO4 with up to nearly half of the magnetic Cu sites replaced by non-magnetic Zn and Mg. Neutron scattering, SQUID magnetometry, and complementary quantum Monte Carlo (QMC) simulations demonstrate that this material is an excellent model system for the study of site percolation of the square-lattice Heisenberg antiferromagnet (SLHAF) in the quantum-spin limit S = 1/2. Carefully oxygen-reduced samples exhibit Néel order up to the percolation threshold for site dilution, zp ≈ 40.7%. For z > 10%, the material exhibits a low-temperature tetragonal (LTT) structural phase, with a transition temperature that increases linearly with doping. Above z ≈ 25%, Néel order occurs in the LTT phase. Up to at least z = 35%, the Néel temperature TN(z) of the experimental system corresponds to the temperature at which QMC indicates that the spin correlations for the nearest-neighbor S = 1/2 SLHAF have grown to approximately 100 lattice constants. Neutron scattering measurements of the static structure factor in the paramagnetic regime allow the determination of the two-dimensional spin correlations, which are found to be in excellent quantitative agreement with QMC over a wide common temperature and doping range. Neutron scattering and QMC results for the temperature dependence of the static structure factor amplitude S(π,π) are in good agreement as well. As the concentration of non-magnetic sites is increased, the magnetic correlation length ξ(T,z) crosses over from an exponential dependence on ρs/T to power-law behavior in the temperature regime studied. Fits to a heuristic cross-over form for ξ(T,z) allow an estimate of the spin stiffness, ρs = ρs(z), which approaches zero at z = zp. The combined experimental and numerical data presented here provide valuable quantitative information for tests of theories of the randomly diluted S = 1/2 SLHAF.

KW - A. Insulators

KW - B. Crystal growth

KW - D. Phase transitions

KW - D. Spin dynamics

KW - E. Neutron scattering

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UR - http://www.scopus.com/inward/citedby.url?scp=0037399674&partnerID=8YFLogxK

U2 - 10.1016/S0038-1098(02)00708-1

DO - 10.1016/S0038-1098(02)00708-1

M3 - Conference article

AN - SCOPUS:0037399674

SN - 0038-1098

VL - 126

SP - 93

EP - 101

JO - Solid State Communications

JF - Solid State Communications

IS - 1-2

T2 - High-Tc Superconductivity Workshop

Y2 - 7 June 2002 through 7 June 2002

ER -

Neutron scattering, magnetometry, and quantum Monte Carlo study of the randomly diluted spin-1/2 square-lattice Heisenberg antiferromagnet

Abstract

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Keywords

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