Abstract
Reentrance, the return of a system from an ordered phase to a previously encountered less-ordered one as a controlled parameter is continuously varied, is a recurring theme found in disparate physical systems, yet its microscopic cause is often not investigated thoroughly. Here, through detailed characterization and theoretical modeling, we uncover the microscopic mechanism behind reentrance in the strongly frustrated pyrochlore antiferromagnet Er2Sn2O7. We use single crystal heat capacity measurements to expose that Er2Sn2O7 exhibits multiple instances of reentrance in its magnetic field B vs temperature T phase diagram for magnetic fields along three cubic high symmetry directions. Through classical Monte Carlo simulations, mean field theory, and classical linear spin-wave expansions, we argue that the origins of the multiple occurrences of reentrance observed in Er2Sn2O7 are linked to soft modes. These soft modes arise from phase competition and enhance thermal fluctuations that entropically stabilize a specific ordered phase, resulting in an increased transition temperature for certain field values and thus the reentrant behavior. Our work represents a detailed examination into the mechanisms responsible for reentrance in a frustrated magnet and may serve as a template for the interpretation of reentrant phenomena in other physical systems.
| Original language | English |
|---|---|
| Article number | 277206 |
| Journal | Physical Review Letters |
| Volume | 127 |
| Issue number | 27 |
| DOIs | |
| State | Published - Dec 31 2021 |
| Externally published | Yes |
Funding
We acknowledge Natalia Perkins for useful discussions and Rob Mann for comments on reentrance in black holes. We thank Allen Scheie and Tom Hogan for their help with analyzing the long pulse measurements, and acknowledge the use of the l ong hcp ulse program for this analysis. We acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the neutron research facilities used in this work. This research was partially supported by CIFAR. D. R. Y., K. A. R., and J. W. K. acknowledge funding from the Department of Energy Award No. DE-SC0020071 during the preparation of this manuscript. The work at the University of Waterloo was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and by the Canada Research Chairs Program (M. J. P. G., Tier 1). L. D. C. J. acknowledges financial support from CNRS (PICS No. 228338) and from the French “Agence Nationale de la Recherche” under Grant No. ANR-18-CE30-0011-01. We thank I. Zivkovic and R. Freitas for providing us their data previously published in Ref. .