Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 21: Frustrated Magnets I
MA 21.9: Talk
Wednesday, March 19, 2025, 11:45–12:00, H18
The role of quantum fluctuations in rare-earth pyrochlore oxides — •Lasse Gresista1, Daniel Lozano-Gómez2, Simon Trebst1, and Yasir Iqbal3 — 1Institute for Theoretical Physics, University of Cologne — 2Institut fur Theoretische Physik and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universitat Dresden — 3Department of Physics and Quantum Center for Diamond and Emergent Materials (QuCenDiEM), Indian Institute of Technology Madras, Chennai, India
Rare-earth pyrochlore oxides provide a rich platform for exploring exotic magnetic phenomena, ranging from the highly degenerate spin-ice states governed by emergent gauge theories in Dy2Ti2O7 and Ho2Ti2O7, to order-by-disorder effects in Er2Ti2O7, multi-phase magnetism in Yb2Ti2O7, and the ongoing quest to realize a quantum spin liquid state in experiment. Many of these materials are well described by localized spin-1/2 moments on a pyrochlore lattice coupled via anisotropic interactions. While the classical limit of this model has been extensively studied, a full quantum mechanical treatment remains challenging. In this work, we investigate the general spin-1/2 Hamiltonian using a pseudo-fermion functional renormalization group approach, which incorporates quantum fluctuations beyond mean-field theory. Our results reveal a significant shift in phase boundaries compared to the classical model, alongside the emergence of disordered regions without conventional magnetic order. This highlights the importance of quantum fluctuations when interpreting experimental observations in pyrochlore magnets.
Keywords: pyrochlore materials; quantum fluctuations; quantum spin liquid; higher-rank gauge theory; functional renormalization group