Abstract
We investigate the quantum Heisenberg model on the pyrochlore lattice for a generic spin in the presence of nearest-neighbor and second-nearest-neighbor exchange interactions. By employing the pseudofermion functional renormalization group method, we find, for and , an extended quantum-spin-liquid phase centered around , which is shown to be robust against the introduction of breathing anisotropy. The effects of temperature, quantum fluctuations, breathing anisotropies, and a coupling on the nature of the scattering profile, and the pinch points, in particular, are studied. For the magnetic phases of the model, quantum fluctuations are shown to renormalize phase boundaries compared to the classical model and to modify the ordering wave vectors of spiral magnetic states, while no new magnetic orders are stabilized.
- Received 5 April 2018
- Revised 11 October 2018
DOI:https://doi.org/10.1103/PhysRevX.9.011005
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
In a frustrated quantum magnet, competing interactions among neighboring electronic spins prevent the system from settling into an ordered ground state near absolute zero temperature—giving rise to an exotic state known as a quantum spin liquid. The leading model for studying 3D frustrated quantum magnets is the Heisenberg model on the pyrochlore lattice. And yet, theoretical analysis of this model is plagued with serious difficulties. Here, we develop a more complete picture of this model by tackling some of these difficulties.
We employ a state-of-the-art methodological framework to explore the effects of quantum fluctuations on the Heisenberg pyrochlore model, a notoriously difficult problem that had not yet been adequately addressed. Our approach allows us to study the onset of these fluctuations as one tunes the length of the spins in the model from infinite down to their lowest permissible value of one-half. The length of the spin thus serves as a knob that can be used to tune the “quantumness” in the system, which is maximal for a length of one-half. Following this procedure, we reveal the presence of extended regions of quantum-spin-liquid behavior.
Our analysis provides a platform to develop a deeper theoretical understanding of pyrochlore magnets, and thus aspires to catalyze the search for 3D spin liquids in quantum materials.
