Quenched crystal field disorder and magnetic liquid ground states in Tb2Sn2-xTixO7

Abstract

Solid-solutions of the "soft" quantum spin ice pyrochlore magnets Tb2B2O7 with B=Ti and Sn display a novel magnetic ground state in the presence of strong B-site disorder, characterized by a low susceptibility and strong spin fluctuations to temperatures below 0.1 K. These materials have been studied using ac-susceptibility and muSR techniques to very low temperatures, and time-of-flight inelastic neutron scattering techniques to 1.5 K. Remarkably, neutron spectroscopy of the Tb3+ crystal field levels appropriate to at high B-site mixing (0.5 < x < 1.5 in Tb2Sn2-xTixO7) reveal that the doublet ground and first excited states present as continua in energy, while transitions to singlet excited states at higher energies simply interpolate between those of the end members of the solid solution. The resulting ground state suggests an extreme version of a random-anisotropy magnet, with many local moments and anisotropies, depending on the precise local configuration of the six B sites neighboring each magnetic Tb3+ ion.

6 pages, 6 figures

References in corpus (8)

• Dirac Strings and Magnetic Monopoles in Spin Ice Dy2Ti2O7
• Dynamically-Induced Frustration as a Route to a Quantum Spin Ice State in Tb2Ti2O7 via Virtual Crystal Field Excitations and Quantum Many-Body Effects
• Spin dynamics and magnetic order in magnetically frustrated Tb2Sn2O7
• Understanding Paramagnetic Spin Correlations in the Spin-Liquid Pyrochlore Tb2Ti2O7
• Direct evidence for a dynamical ground state in the highly frustrated Tb${}_2$Sn${}_2$O${}_7$ pyrochlore
• Antiferromagnetic Spin Ice Correlations at (1/2,1/2,1/2) in the Ground State of the Pyrochlore Magnet Tb2Ti2O7
• Crystal Field and Magnetoelastic Interactions in Tb2Ti2O7
• Low temperature dynamic freezing and the fragility of ordering in Tb2Sn2O7

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• Absence of moment fragmentation in the mixed $B$-site pyrochlore Nd${}_2$GaSbO${}_7$
• Traversing the pyrochlore stability diagram; microwave-assisted synthesis and discovery of mixed B-site Ln${}_2$InSbO${}_7$ family
• Collective magnetic state induced by charge disorder in the non-Kramers rare-earth pyrochlore Tb${}_2$ScNbO${}_7$