Magnetic Order with Fractionalized Excitations: Applications to ${\mathrm{Yb}}_2{\mathrm{Ti}}_2{\mathrm{O}}_7$

Abstract

A recent inelastic neutron scattering experiment on ${\mathrm{Yb}}_2{\mathrm{Ti}}_2{\mathrm{O}}_7$ uncovers an unusual scattering continuum in the spin excitation spectrum despite the splayed ferromagnetic order in the ground state. While there exist well defined spin wave excitations at high magnetic fields, the one magnon modes and the two magnon continuum start to strongly overlap upon decreasing the field, and eventually they become the scattering continuum at zero field. Motivated by these observations, we investigate the possible emergence of a magnetically ordered ground state with fractionalized excitations in the spin model with the exchange parameters determined from two previous experiments. Using the fermionic parton mean field theory, we show that the magnetically ordered state with fractionalized excitations can arise as a stable mean field ground state in the presence of sufficiently strong quantum fluctuations. The spin excitation spectrum in such a ground state is computed and shown to have the scattering continuum. Upon increasing the magnetic field, the fractionalized magnetically ordered state is suppressed, and is eventually replaced by the conventional magnetically ordered phase at high fields, which is consistent with the experimental data. We discuss further implications of these results to the experiments and possible improvements on the theoretical analysis.

18 pages, 12 figures, 6 tables

References in corpus (9)

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Cited by in corpus (11)

• Multiphase Magnetism in Yb2Ti2O7
• Magnon interactions in the frustrated pyrochlore ferromagnet Yb${}_2$Ti${}_2$O${}_7$
• Competing $U(1)$ and ${\mathbb{Z}}_2$ dipolar-octupolar quantum spin liquids on the pyrochlore lattice: application to Ce${}_2$Zr${}_2$O${}_7$
• Symmetry fractionalization in the gauge mean-field theory of quantum spin ice
• Symmetric $\mathrm{U}(1)$ and ${\mathbb{Z}}_2$ spin liquids on the pyrochlore lattice
• Coexistence of non-Abelian chiral spin liquid and magnetic order in a spin-1 antiferromagnet
• Competing quantum spin liquids, gauge fluctuations, and anisotropic interactions in a breathing pyrochlore lattice
• Beyond magnons in Nd2ScNbO7: An Ising pyrochlore antiferromagnet with all in all out order and random fields
• Orientation Dependence of the Magnetic Phase Diagram of Yb${}_2$Ti${}_2$O${}_7$
• Magnetic Field Response of Dipolar-Octupolar Quantum Spin Ice
• Towards a global phase diagram of Ce-based dipolar-octupolar pyrochlore magnets under magnetic fields