Tunable Magnon Interactions in a Ferromagnetic Spin-1 Chain

Prashant Chauhan, Fahad Mahmood, Hitesh J. Changlani, S. M. Koohpayeh, N. P. Armitage

Research output: Contribution to journalArticlepeer-review

Abstract

NiNb2O6 is an almost ideal realization of a 1D spin-1 ferromagnetic Heisenberg chain compound with weak unidirectional anisotropy. Using time-domain THz spectroscopy, we measure the low-energy electrodynamic response of NiNb2O6 as a function of temperature and external magnetic field. At low temperatures, we find a magnonlike spin excitation, which corresponds to the lowest energy excitation at q∼0. At higher temperatures, we unexpectedly observe a temperature-dependent renormalization of the spin-excitation energy, which has a strong dependence on field direction. Using theoretical arguments, exact diagonalizations, and finite temperature dynamical Lanczos calculations, we construct a picture of magnon-magnon interactions that naturally explains the observed renormalization. We show how magnetic field strength and direction may be used to directly tune the sign of the magnon-magnon interaction. This unique scenario is a consequence of the spin-1 nature and has no analog in the more widely studied spin-1/2 systems.

Original languageEnglish (US)
Article number037203
JournalPhysical review letters
Volume124
Issue number3
DOIs
StatePublished - Jan 23 2020
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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