Spin-glass and non–spin-glass features of a geometrically frustrated magnet

¹ Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
² National Institute of Standards and Technology - Gaithersburg, MD 20899, USA
³ NEC - 4 Independence Way, Princeton, NJ 08540, USA
⁴ AT&AT Bell Laboratories - 600 Mountain Ave., Murray Hill, NJ 07974, USA
⁵ ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, UK
⁶ Royal Dutch Shell Laboratories, P.O. Box 3003, 1003 AA Amsterdam, The Netherlands

Received: 9 February 1996
Accepted: 24 May 1996

Abstract

We use neutron scattering to show that the low-temperature, short-range ordered spin configuration in the geometrically frustrated magnet (p=0.92(5)) is composed of small groups of spins whose dipole moments cancel. The local magnetic fluctuation spectrum, , vanishes approximately in proportion to ω for , distinguishing this magnet from conventional spin glasses which display a featureless continuum of excited states. We argue that this behavior results from the absence of local, low-energy excitations in the zero-spin clusters from which the frozen spin configuration is composed.