@article{dfab67c1c9fb4635b88497c1ff136984,
title = "Neutron scattering study of Sr2Cu3O4Cl2",
abstract = "We report a neutron scattering study on the tetragonal compound Sr2Cu3O4Cl2, which has two-dimensional (2D) interpenetrating CuI and CuII subsystems, each forming a S = 1/2 square lattice quantum Heisenberg antiferromagnet (SLQHA). The mean-field ground state is degenerate, since the intersubsystem interactions are geometrically frustrated. Magnetic neutron scattering experiments show that quantum fluctuations lift the degeneracy and cause a 2D Ising ordering of the CuII subsystem. Due to quantum fluctuations a dramatic increase of the CuI out-of-plane spin-wave gap is also observed. The temperature dependence and the dispersion of the spin-wave energy are quantitatively explained by spin-wave calculations which include quantum fluctuations explicitly. The values for the nearest-neighbor superexchange interactions between the CuI and CuII ions and between the CuII ions are determined experimentally to be JI-II= -10(2) meV and JII = 10.5(5) meV, respectively. Due to its small exchange interaction JII, the 2D dispersion of the CuII SLQHA can be measured over the whole Brillouin zone with thermal neutrons, and a dispersion at the zone boundary, predicted by theory, is confirmed. The instantaneous magnetic correlation length of the CuII SLQHA is obtained up to a very high temperature, T/JII≈0.75. This result is compared with several theoretical predictions as well as recent experiments on the S = 1/2 SLQHA.",
author = "Kim, {Y. J.} and Birgeneau, {R. J.} and Chou, {F. C.} and M. Greven and Kastner, {M. A.} and Lee, {Y. S.} and Wells, {B. O.} and A. Aharony and O. Entin-Wohlman and Korenblit, {I. Ya} and Harris, {A. B.} and Erwin, {R. W.} and G. Shirane",
year = "2001",
doi = "10.1103/PhysRevB.64.024435",
language = "אנגלית",
volume = "64",
pages = "244351--2443519",
journal = "Physical Review B - Condensed Matter and Materials Physics",
issn = "0163-1829",
publisher = "American Physical Society",
number = "2",
}