Intrinsic quantum disorder in Yb2Ti2O7 and the quantum S=1/2 pyrochlore phase diagram

TL;DR

This study combines experimental neutron scattering and theoretical modeling to explore the quantum phase diagram of Yb2Ti2O7, revealing intrinsic disorder, emergent quantum phases, and quantum criticality in this pyrochlore system.

Contribution

It provides new insights into the quantum phase diagram of Yb2Ti2O7, identifying an emergent quantum phase and demonstrating quantum criticality as a generic feature.

Findings

Intrinsic broadening and flat magnon mode observed in neutron scattering.

Existence of an emergent quantum phase between ferromagnetic and antiferromagnetic states.

Yb2Ti2O7 can be tuned from magnons to a quantum ground state via magnetic field.

Abstract

We present an experimental and theoretical study of the anisotropic pyrochlore phase diagram. Inelastic field-dependent neutron scattering on Yb$_2$Ti$_2$O$_7$ shows intrinsic broadening and a flat low-energy magnon mode which is partially captured by interacting magnon models. Exact diagonalization reveals the existence of an emergent quantum phase between ferromagnetism and antiferromagnetism, in which Yb$_2$Ti$_2$O$_7$ Hamiltonian potentially resides. This behavior matches the phenomenology of quantum criticality in heavy fermion systems, and shows Yb$_2$Ti$_2$O$_7$ is a clean system which can be field-tuned from well-defined magnons to a nontrivial quantum ground state. This suggests that quantum criticality is a generic feature of the dipolar phase diagram.