2025/02/19 by J. C. G. Henriques, Henriques, J. C. G., Chenxiao Zhao +12 · 1 voice
Chemistry · Engineering · Physics and Astronomy · #Advanced Materials Characterization Techniques #Advanced Physical and Chemical Molecular Interactions #Crystallography and Radiation Phenomena #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.2502.13770
openalex publication_date 2025/02/19 · arxiv published 2025/02/19 · arxiv updated 2025/02/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Conventional methods to measure the dispersion relations of collective spin excitations involve probing bulk samples with particles such as neutrons, photons or electrons, which carry a well-defined momentum. Open-ended finite-size spin chains, on the contrary, do not have a well-defined momentum due to the lack of translation symmetry, and their spin excitations are measured with an eminently local probe, using inelastic electron tunneling spectroscopy (IETS) with a scanning tunneling microscope (STM). Here we discuss under what conditions STM-IETS spectra can be Fourier-transformed to yield dispersion relations in these systems. We relate the success of this approach to the degree to which spin excitations form standing waves. We show that STM-IETS can reveal the energy dispersion of magnons in ferromagnets and triplons in valence bond crystals, but not that of spinons, the spin excitations in Heisenberg spin-1/2 chains. We compare our theoretical predictions with state-of-the-art measurements on nanographene chains that realize the relevant spin Hamiltonians.