Magnetic frustration in rare-earth zirconates A2Zr2O7, the case of laser heated pedestal method synthesised A = Er, Tm, Yb, and Lu single crystals

Low-temperature properties of magnetically frustrated rare-earth zirconates A 2Zr2O7

“…That is, Eu 2 Zr 2 O 7 was used for the pyrochlore zirconates, and Lu 2 Zr 2 O 7 and Y 2 Zr 2 O 7 for defect-fluorite members. We note that Lu 2 Zr 2 O 7 crystallises not in the defectfluorite structure, but in a slightly distorted lower-symmetry rhombohedral structure [24,28]. Nevertheless, it still represents a good estimate of the non-magnetic contributions to the specific heat for the defect-fluorite zirconates, especially the later-rare-earth ones.…”

“…No freezing of spins was observed down to low temperature in Gd 2 Zr 2 O 7 and Ho 2 Zr 2 O 7 , unless a magnetic field was applied [37,38]. Our very recent study on newly prepared single crystals [28] indicates the magnetic properties of Tm 2 Zr 2 O 7 are dictated primarily by its crystal electric field, while short-range correlations and spin freezing were observed in Yb 2 Zr 2 O 7 member.…”

“…The good fit of the diffraction patterns using the standard pyrochlore and defect-fluorite structural models indicated that the single-phase samples have nominal stoichiometry. La 2 Zr 2 O 7 , Nd 2 Zr 2 O 7 and Eu 2 Zr 2 O 7 patterns were described by model pyrochlore structure (Fd-3m); A = Y, Gd-Tm data were Rietveld fitted to the defect-fluorite structure model (Fm-3m); and Lu 2 Zr 2 O 7 was verified to crystallise in lower-symmetry rhombohedral (R-3) structure [24,28], see figure 1. The refined lattice parameters are listed in table 1.…”

“…The local structure of the heavy rare-earth zirconates differs from their average defect-fluorite structure. The local structure was identified to be the same as the average structure of Lu 2 Zr 2 O 7 [28]. Y 2 Zr 2 O 7 was used as a non-magnetic analogue for A = Gd-Ho zirconates, considering a similar lattice parameter and ratio of atomic radii r A /r Zr , see table 1.…”

“…Several A 2 B 2 O 7 members were found to crystallise in lower-symmetry structures: monoclinic [22], orthorhombic [23], and very recently Lu 2 Zr 2 O 7 was reported to adopt a rhombohedral structure (space group R-3) [24]. Moreover, there is an intense discussion about the local crystal structure in these materials diverging significantly from their average structure due to shortrange correlations [25][26][27][28][29]. That is, a strict classification of the respective average crystal structures can be misleading, as the underlying local correlations play a crucial role in interpreting the complex magnetic behaviour reported in these compounds.…”