Orbital physics in sulfur spinels: ordered, liquid and glassy ground states

Spin glass behavior in frustrated quantum spin system CuAl2O4with a possible orbital liquid state

“…2). It is interesting to note that the magnetic entropy of FeCr2S4 single crystal, a candidate for an orbital glass state, reaches just over 2 J/mol-K at 20 K, which is again much smaller than the theoretical value of the combined spin and orbital entropy, Rln2+Rln5 [26].…”

Spin frustration and magnetic exchange in cobalt aluminum oxide spinels

“…We would like to emphasize that the observation of very similar CW temperatures of the order of -110 K for compositions with different Co concentrations on the B-sites apparently excludes the inversion mechanism suggested earlier as reason for the enhanced CW temperature of CoAl 2 O 4 and of the other magnetic A-site aluminum-oxide spinels. 23,25 The alternative explanation 18 based on the high multiplicity of the superexchange interactions between the A-site Co 2+ ions seems to be more plausible. However, the fact that the magnetic exchange in our system is equally strong for both B-site Co 3+ ions in a low-spin 3d 6 state and diamagnetic Al 3+ ions is surprising.…”

“…18, where the large Θ CW was attributed to a high multiplicity of the exchange interaction paths between the tetrahedral ions, which include at least three intermediate ions. 17,24,25 The magnetic structure of Co-Al-O spinels is also far from being clarified. Earlier neutron-diffraction studies 24 26 However, the recent theoretical analysis of the spin order in A-site magnetic spinels 22 does not support such a simple spin arrangement.…”

Magnetic characterization of the sawtooth-lattice olivinesZnL2S4(L=ErLau1, Ueland2, Freitas3 et al. 2006Phys. Rev. B280230View full textAdd to dashboardCite

“…Magnetic atoms arranged in a corner-sharing tetrahedral motif are found in pyrochlore and spinel lattices, and studies have yielded many examples of novel physics associated with frustration in such structures. 1,2 Examples of such frustration have been found in the transition metal sulfide spinels, 3,4,5 with frustration of the structural degrees of freedom even leading to a ferroelectric state in CdCr 2 S 4 . 6 The rare earth spinels, CdLn 2 Se 4 (Ln = Dy, Ho) and CdLn 2 S 4 (Ln = Ho, Er, Tm, Yb), also appear to be frustrated, showing no magnetic ordering down to T = 2 K and only reaching partial saturation of the full expected moment up to applied fields of H = 9 T. 7 The work on these thio-spinels suggests that investigating the magnetic properties of sulfides in the olivine structure, a structure type closely related to the spinel structure, should be of interest from the viewpoint of magnetic frustration.…”