Ordering due to Quantum Fluctuations in <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">Sr</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow><mrow><msub><mrow><mi mathvariant="normal">Cu</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow><mrow><msub><mrow><mi mathvariant="normal">O</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow><mrow><msub><mrow><mi mathvariant="normal">Cl</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span>

Y. J. Kim; A. Aharony; R. J. Birgeneau; F. C. Chou; O. Entin-Wohlman; R. W. Erwin; M. Greven; A. B. Harris; M. A. Kastner; I. Ya. Korenblit; Y. S. Lee; G. Shirane

doi:10.1103/PhysRevLett.83.852

Ordering due to Quantum Fluctuations in ${Sr}_{2} {Cu}_{3} O_{4} {Cl}_{2}$

Y. J. Kim, A. Aharony, R. J. Birgeneau, F. C. Chou, O. Entin-Wohlman, R. W. Erwin, M. Greven, A. B. Harris, M. A. Kastner, I. Ya. Korenblit, Y. S. Lee, and G. Shirane

Phys. Rev. Lett. 83, 852 – Published 26 July 1999

Abstract

${Sr}_{2} {Cu}_{3} O_{4} {Cl}_{2}$ has ${Cu}_{I}$ and ${Cu}_{II}$ subsystems, forming interpenetrating $S = 1 / 2$ square lattice Heisenberg antiferromagnets. The classical ground state is degenerate, due to frustration of the intersubsystem interactions. Magnetic neutron scattering experiments show that quantum fluctuations cause a two dimensional Ising ordering of the ${Cu}_{II}$ 's, lifting the degeneracy, and a dramatic increase of the ${Cu}_{I}$ out-of-plane spin-wave gap, unique for order out of disorder. The spin-wave energies are quantitatively predicted by calculations which include quantum fluctuations.

Received 4 January 1999

DOI:https://doi.org/10.1103/PhysRevLett.83.852

Authors & Affiliations

Y. J. Kim^1,2, A. Aharony³, R. J. Birgeneau¹, F. C. Chou¹, O. Entin-Wohlman³, R. W. Erwin⁴, M. Greven^1,*, A. B. Harris⁵, M. A. Kastner¹, I. Ya. Korenblit³, Y. S. Lee¹, and G. Shirane⁶

¹Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
²Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
³School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
⁴National Institute of Standards and Technology, Gaithersburg, Maryland 20899
⁵Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
⁶Department of Physics, Brookhaven National Laboratory, Upton, New York 11973