Spin dynamics in a two-dimensional disordered S=(1)/(2) Heisenberg paramagnet from {sup 63}Cu NQR relaxation in Zn-doped La{sub 2}CuO{sub 4}

Journal Article · Sat Feb 01 04:00:00 EST 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.55.3734· OSTI ID:450387

Carretta, P; Rigamonti, A; Sala, R ^[1]

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1. Department of Physics A. Volta, Unita INFM and Sezione INFN di Pavia, Via Bassi, 6, 27100-I Pavia (Italy)

{sup 63}Cu NQR T{sub 1} and T{sub 2} relaxation measurements in La{sub 2}Cu{sub 1{minus}x}Zn{sub x}O{sub 4}, for 0{le}x{le}0.11 and in the temperature range T{sub N}{le}T{le}900 K, are presented. The results are used to derive insights into the Cu{sup 2+} correlated spin dynamics in the paramagnetic phase of the S=(1)/(2) two-dimensional (2D) Heisenberg (H) antiferromagnets (AF), and into the disorder effects associated with the spin vacancy due to Zn{sup 2+} (S=0) for Cu{sup 2+} substitution. In particular, by using scaling arguments for the static generalized susceptibility, {chi}({rvec q},0), and for the decay rate, {Gamma}{sub {rvec q}}, of the normal excitations, T{sub 2} and T{sub 1} are related to the in-plane correlation length {xi}{sub 2D}(x,T) and its dependence on temperature and Zn doping, x, is extracted. The experimental findings are analyzed in light of the quantum critical and renormalized classical behaviors for {xi}{sub 2D} predicted by recent theories for S=1/2 HAF on square lattices. It is shown that up to T{approx_equal}900 K, {xi}{sub 2D} is consistent with the assumption of a renormalized classical regime, in agreement with recent neutron scattering results and at variance with previous interpretations of the NQR data. It is discussed how Zn affects {xi}{sub 2D} through the modification in the spin stiffness and comparison with the disorder induced by itinerant extra holes is made.

• OSTI ID: 450387
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 6 Vol. 55; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIFERROMAGNETIC MATERIALS
COPPER OXIDES
HEISENBERG MODEL
HIGH-TC SUPERCONDUCTORS
LANTHANUM OXIDES
LATTICE PARAMETERS
MAGNETIC SUSCEPTIBILITY
NUCLEAR QUADRUPOLE RESONANCE
PHASE TRANSFORMATIONS
SPIN-SPIN RELAXATION