Magnetic frustration in the disordered pyrochlore Yb₂GaSbO₇

Abstract

In the pyrochlore Yb(2)GaSbO(7), the Yb(3+) sublattice forms a network of corner sharing tetrahedra and the second sublattice is made up of disordered, non-magnetic Ga(3+) and Sb(5+) ions. We have examined this compound using magnetic susceptibility, (170)Yb Mössbauer spectroscopy (down to 0.03 K) and muon spin relaxation (μSR) (down to 0.02 K) measurements. We establish the size of the Yb(3+) magnetic moments and that of the Yb(3+)-Yb(3+) coupling. At low temperatures, the correlated moments fluctuate between directions that are well tilted relative to the local [111] axis. The lattice disorder does not quench the frustration induced low temperature spin fluctuations but it does remove the first order dynamic transition that is present in the crystallographically ordered counterpart Yb(2)Ti(2)O(7). Below 1.0 K, the fluctuation rate of the correlated moments decreases progressively as the temperature is reduced and the moments remain dynamic down to 0.02 K where the rate is 7 × 10(7) s(-1). Magnetic frustration is operative in Yb(2)GaSbO(7) where the Yb(3+)-Yb(3+) interaction is antiferromagnetic as it is in Yb(2)Ti(2)O(7) where the interaction is ferromagnetic.

Dynamical Splayed Ferromagnetic Ground State in the Quantum Spin IceYb2Sn2O7

“…This result directly evidences the strong easy-axis anisotropy of the exchange in Yb 2 Sn 2 O 7 , as already noticed for Yb 2 Ti 2 O 7 [27,28] and Yb 2 GaSbO 7 [29].…”

“…As in Refs. [12,29], to extract c; from Z , we first identify it with c;M . Since at 0.2 K we have c;M ' 2:08 Â 10 10 s À1 To ensure a good thermal contact, the powder was placed in a copper container filled at room temperature with 10 bars of helium and sealed.…”

Absence of moment fragmentation in the mixed B -site pyrochlore Nd2GaSbO7

“…Notable examples include the mixed A-site fluoride pyrochlore NaCaCo 2 F 7 [27], which is argued to form a disorder-induced cluster spin-glass phase [28], and the related pyrochlore NaCaNi 2 F 7 [29], which exhibits disorder-induced spin freezing that appears to preempt a Heisenberg spin-liquid state. In addition, the mixed B-site oxide pyrochlore Yb 2 GaSbO 7 [30] is a candidate for disorder-induced spin liquid or spin-singlet behavior [31]. Interestingly, Nd 2 ScNbO 7 shows the combination of AIAO long-range magnetic order and diffuse scattering expected for moment fragmentation, although open questions remain about the true nature of its magnetic ground state and the presence of this exotic phenomenon in this material [32,33].…”

Single-ion properties of the $S_{eff}$ = 1/2 XY antiferromagnetic pyrochlores, Na$A^{\prime}$Co$_2$F$_7$ ($A^{\prime} = $ Ca$^{2+}$, Sr$^{2+}$)

“…An interesting comparison in this regard can be made to the B-site disordered Yb-based pyrochlore Yb 2 GaSbO 7 ; with its θ CW = −1.15 K and lack of a freezing transition down to the lowest measured temperature of 20 mK, this material demonstrates similarly "ineffective" exchange disorder relative to its (much weaker) average interaction strength (f ≥ 58). 24,25 Unlike the rare earth oxides, nearly ideal Heisenberg moments with large spins should be expected for most of the members in this new series of transition metal flu-oride pyrochlores. This is due to the quenching of orbital angular momentum expected for most octahedrally coordinated 3d transition metals.…”