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

Abstract

We use neutron scattering to show that the low-temperature, short-range ordered spin configuration in the geometrically frustrated magnet SrCr 9p Ga12−9p O19 (p = 0.92(5)) is composed of small groups of spins whose dipole moments cancel. The local magnetic fluctuation spectrum, χ (ω), vanishes approximately in proportion to ω for hω < 0.5 meV, 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.

Macroscopic Signature of Protected Spins in a Dense Frustrated Magnet

“…1e) for h ac < h A than for h ac > h A . Indeed, the imaginary part of the bulk response should be rigorously zero [20] for h ac → 0 for a clean Heisenberg magnet (with h A = 0) consisting of AFM triangles.…”

Effect of Chemical Disorder on Geometrically Frustrated Kagome Lattice

“…The magnetic susceptibility measurements (macroscopic, χ macro , in contrast to local measurements by NMR technique [10]) suggest the occurrence of spin glass state with spin freezing temperature T g ≈ 2-5 K [11][12][13][14][15]. All other experimental data confirms existence of a spin-liquid-like ground state [12,16,17]. In particular, neutron diffraction experiments indicate the existence of subgroups of spins (singlets, triangles, etc.)…”

“…In particular, neutron diffraction experiments indicate the existence of subgroups of spins (singlets, triangles, etc.) [17] and lead to the conclusion that only a fraction of the Cr 3+ moments is frozen. The magnetic lattice of SrGa 12−x Cr x O 19 is specific because it consists of kagome bilayers of Cr 3+ ions separated by Cr-Cr isolated spin pairs.…”

Néel to spin-glass-like phase transition versus dilution in geometrically frustratedZnCr2−2xGa2xLee1, Ratcliff2, Huang3 et al. 2008Phys. Rev. B

“…One can increase the complexity of this problem by considering the case of the even less constrained system of corner sharing triangles, the kagome lattice. [4,8,9,10,11] There have been many theoretical questions about the nature of the ground state [12,13,14,15] even for classical spins on this lattice. [5,6,7] Experimentally, good experimental realizations of this system have been hard to obtain.…”