Terahertz study of the frustrated triangular Ising magnet FeI2

ORAL

Abstract

2D antiferromagnetic (AF) triangular lattices are of great interest due to their geometric frustration, which may lead to the absence of a long-range magnetic order at T=0. FeI2 is part of the ferrous halides family, in which the Fe2+ ions are distributed on hexagonal planes and spontaneously order in an AF phase below TN∼9K [1]. Contrary to other ferrous halides, the spins in the ordered phase of FeI2 form triangular AF sheets (instead of antiparallel ferromagnetic sheets), giving rise to a more complex magnetic structure. In this peculiar ground state, the spins (S=1) generate several types of magnetic excitations, including a mysterious two-magnon bound state that should be prevented by selection rules [2]. Moreover, when an external magnetic field is applied along the c-axis at T<TN, successive magnetic transitions occur, including a phase without evidence of long-range order [3]. We present the results from in-field time-domain terahertz spectroscopy on FeI2. These experiments give insight into the diverse magnetic excitations of this triangular AF lattice.
[1] Bertrand et al., J. Phys. 35, 385 (1974)
[2] Petitgrand et al., JMMM 15-18, 381 (1980)
[3] Fert et al., Sol. St. Comm. 13, 1219 (1973)

–

Presenters

  • Anaelle Legros

    Johns Hopkins University, Universite de Sherbrooke

Authors

  • Anaelle Legros

    Johns Hopkins University, Universite de Sherbrooke

  • Dipanjan Chaudhuri

    Johns Hopkins University

  • Xiaojian Bai

    Georgia Inst of Tech, School of Physics, Georgia Institute of Technology, Georgia Institute of Technology

  • Zhiling Dun

    Georgia Inst of Tech, School of Physics, Georgia Institute of Technology, Physics, Georgia Institute of Technology, Georgia Institute of Technology

  • Martin Mourigal

    Georgia Inst of Tech, School of Physics, Georgia Institute of Technology, Physics, Georgia Institute of Technology, Georgia Institute of Technology

  • Peter Armitage

    Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, Johns Hopkins University, Institute of Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University