Chenxiao Zhao^1*, Lin Yang², João Henriques³, Mar Ferri-Cortés⁴, Gonçalo Catarina¹, Carlo A. Pignedoli¹, Ji Ma², Xinliang Feng^5,2*, Pascal Ruffieux^1*, Joaquín Rossier^3*, Roman Fasel^1,6*

1 Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland

2 Max Planck Institute of Microstructure Physics, Halle, Germany

3 International Iberian Nanotechnology Laboratory, Braga, Portugal.

4 Departamento de Física Aplicada, Universidad de Alicante, San Vicente del Raspeig, Alicante, Spain

5 Faculty of Chemistry and Food Chemistry, and Center for Advancing Electronics Dresden, Technical University of Dresden, Dresden, Germany

6 University of Bern, Bern, Switzerland

* Corresponding authors emails: chenxiao.zhao@emap.ch, xinliang.feng@tu-dresden.de, pascal.ruffieux@empa.ch, oaquin.fernandez-rossier@inl.int, roman.fasel@empa.ch

DOI10.24435/materialscloud:zx-87 [version v1]

Publication date: Jan 22, 2025

How to cite this record

Chenxiao Zhao, Lin Yang, João Henriques, Mar Ferri-Cortés, Gonçalo Catarina, Carlo A. Pignedoli, Ji Ma, Xinliang Feng, Pascal Ruffieux, Joaquín Rossier, Roman Fasel, Spin excitations in nanographene-based antiferromagnetic spin-½ Heisenberg chains, Materials Cloud Archive 2025.16 (2025), https://doi.org/10.24435/materialscloud:zx-87

Description

Antiferromagnetic Heisenberg chains exhibit two distinct types of excitation spectra: gapped for integer-spin chains and gapless for half-integer-spin chains. However, in finite-length half-integer-spin chains, quantization induces a gap, requiring precise control over sufficiently long chains to study its evolution. In a recent publication, we created length-controlled spin-1/2 Heisenberg chains by covalently linking olympicenes—Olympic ring-shaped magnetic nanographenes. With large exchange interactions, tunable lengths, and negligible magnetic anisotropy, this system is ideal for investigating length-dependent spin excitations, probed via inelastic electron tunneling spectroscopy. We observe a power-law decay of the lowest excitation energy with length L, following a 1/L dependence in the large-L regime, consistent with theory. For L=50, a V-shaped excitation continuum confirms gapless behavior in the thermodynamic limit. Additionally, low-bias current maps reveal the standing wave of a single spinon in odd-numbered chains. Our findings provide evidence for the realization of a one-dimensional analog of a gapless spin liquid within an artificial graphene lattice. This record includes all the data that support the results discussed in the publication.

Materials Cloud sections using this data

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Keywords

spin liquid spin excitation fractional excitation spinon DFT MARVEL/P4 CSCS