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  • Excitations of quantum Ising chain CoNb2O6 in low transverse field: Quantitative description of bound states stabilized by off-diagonal exchange and applied field
Title: Excitations of quantum Ising chain CoNb2O6 in low transverse field: Quantitative description of bound states stabilized by off-diagonal exchange and applied field
We present experimental and theoretical evidence of novel bound state formation in the low transverse field or- dered phase of the quasi-one-dimensional Ising-like material CoNb2O6. High-resolution single-crystal inelastic neutron scattering measurements observe that small transverse fields lead to a breakup of the spectrum into three parts, each evolving very differently upon increasing field. This can be naturally understood starting from the excitations of the ordered phase of the transverse field Ising model, domain wall quasiparticles (solitons). Here, the transverse field and a staggered off-diagonal exchange create one-soliton hopping terms with opposite signs. We show that this leads to a rich spectrum and a special field, when the strengths of the off-diagonal exchange and transverse field match, at which solitons become localized; the highest field investigated is very close to this special regime. We solve this case analytically and find three two-soliton continua, along with three novel bound states. Perturbing away from this novel localized limit, we find very good qualitative agreement with the experimental data. We also present calculations using exact diagonalization of a recently refined Hamiltonian model for CoNb2O6 and using diagonalization of the two-soliton subspace, both of which provide a quantitative agreement with the observed spectrum. The theoretical models qualitatively and quantitatively capture a variety of nontrivial features in the observed spectrum, providing insight into the underlying physics of bound state formation.  more » « less
Award ID(s):
2116515
PAR ID:
10538885
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Physical Review B
Date Published:
Journal Name:
Physical Review B
Volume:
108
Issue:
18
ISSN:
2469-9950
Page Range / eLocation ID:
184417
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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