We investigate spin-flip excitations in the spin-1/2 trimer chain Cu3(P2O6OH)2, featuring an antiferromagnetic exchange motif J1-J1-J2 with J1<J2. Using density matrix renormalization group (DMRG) simulations, we demonstrate that single-spin-flip processes induced by resonant inelastic X-ray scattering (RIXS) generate emergent gapless modes governed by the underlying trimer periodicity alongside distinct high-energy excitations. By combining exact diagonalization and real-space renormalization group (RG) techniques, we attribute these features to fractionalized spinons and composite quasiparticles arising from one- and two-trimer excitations. Furthermore, we show that multi-spin RIXS excitations yield experimentally distinguishable spectral signatures of composite modes absent in single-spin-flip spectra. At the field-induced 1/3 magnetization plateau, single-spin-flip RIXS spectra evolves with the magnetic field to favor spin-polarized composite quasiparticles. This trend culminates in a gapless spectrum of spin-1 excitations beyond the plateau, paving the way for field-tuned Bose condensation of composite modes.
@article{arxiv.2505.23208,
title = {Emergent Quasiparticles \& Field-Tuned RIXS Spectra in a Trimerized Spin-1/2 Chain},
author = {Subhajyoti Pal and Pradeep Thakur and Ashis Kumar Nandy and Anamitra Mukherjee},
journal= {arXiv preprint arXiv:2505.23208},
year = {2025}
}