Frustration Induced Spin Freezing in a Site-Ordered Magnet: Gadolinium Gallium Garnet

Magnetothermal study of a Dy-stuffed spin ice:Dy2(DyxTi2−x)Ueland1, Lau2, Freitas3 et al. 2008Phys. Rev. BSelf Cite16140View full textAdd to dashboardCite

“…The finite susceptibility as T ~ 0 in Dy SSI, however, indicates that some spins remain fluctuating down to the lowest temperatures measured -a somewhat curious result since stuffing in more Dy ions yields a higher density of spins and stronger average spin-spin interactions. (GGG), showing a broad peak at higher temperatures, which was found to correspond to the quenching of local antiferromagnetic correlations [7]. The two peaks which evolve at lower temperatures are also reminiscent of the (much sharper) peaks associated with field-induced long range order in that material [9].…”

“…The energy scales of the interactions in these magnets offer unique opportunities to study how frustrated thermodynamic systems settle into their lowest energy states [1,2,3]. Examples of novel ground states observed in geometrically frustrated magnets include spin-glass-like states despite the presence of minimal structural disorder [4,5,6,7], cooperative paramagnetic states, in which the spins are locally correlated yet continue to fluctuate as T ~ 0 [8,9,10,11], and spin ice states [12,13,14,15,16,17,18,19,20,21], in which the spins freeze into a state analogous to that of the protons in frozen water. In this paper we report experimental results for variants of two spin ice materials, formed by increasing the density of spins present in the materials.…”

Dirty spin ice: The effect of dilution on spin freezing inDy2Ti2OSnyder1, Slusky2, Cava3 et al. 2002Phys. Rev. BSelf Cite484330View full textAdd to dashboardCite

“…Furthermore, since the magnitude of the freezing signature but not the other parameters characterizing the magnetic relaxation at T ~ 16 K are strongly affected by dilution, it appears that the freezing at that temperature reflects only the development of short range correlations (since longer range correlations would be affected by dilution). We conclude that the "spin ice" freezing is most likely occurring in two stages: at T ~ 16 K, spins develop short-range correlations (presumably in local units of tetrahedra or larger) but they continue to fluctuate at low frequencies, and then long range freezing is achieved upon further cooling to below T ~ 2 K. This sort of two-stage freezing has also been seen in a.c. susceptibility studies of the spin-glass-like freezing of the geometrically frustrated garnet Gd 3 Ga 5 O 12 [ 38], and future investigations may show it to be a common feature in other geometrically frustrated magnetic materials. …”

Spin Hamiltonian, Competing Small Energy Scales, and Incommensurate Long-Range Order in the Highly FrustratedGd3Ga5O12Garnet Antiferromagnet

“…In zero magnetic field, the behavior of GGG is uniquely rich. The nonlinear magnetic susceptibility χ 3 peaks at T g ∼ 180 mK [4], indicating a spin glass transition [5]. However, muon spin relaxation [6,7] and Mössbauer spectroscopy [8] find persistent spin dynamics down to T ≪ T g .…”

“…It assumes classical Gd 3+ spins, is parameterized as a sum of empirical exchange contributions up to third nearestneighbors as well as a magnetic dipolar contribution, and ignores potentially important quantum fluctuations or disorder inherent to GGG [4]. Previous numerical studies based on H have been unable to provide a quantitative explanation for the bulk [4] and dynamical [6,7,8] properties of GGG or the incommensurate spin-spin correlations that develop below 200 mK [9,10]. This could be interpreted as evidence that exotic mechanisms involving either quantum fluctuations or disorder effects are at play in GGG.…”