Observation of fractional edge excitations in nanographene spin chains

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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:creator>Mishra, Shantanu</dc:creator>
  <dc:creator>Catarina, Gonçalo</dc:creator>
  <dc:creator>Wu, Fupeng</dc:creator>
  <dc:creator>Ortiz, Ricardo</dc:creator>
  <dc:creator>Jacob, David</dc:creator>
  <dc:creator>Eimre, Kristjan</dc:creator>
  <dc:creator>Ma, Ji</dc:creator>
  <dc:creator>Pignedoli, Carlo A.</dc:creator>
  <dc:creator>Feng, Xinliang</dc:creator>
  <dc:creator>Ruffieux, Pascal</dc:creator>
  <dc:creator>Fernández-Rossier, Joaquín</dc:creator>
  <dc:creator>Fasel, Roman</dc:creator>
  <dc:date>2021-10-11</dc:date>
  <dc:description>Fractionalization is a phenomenon in which strong interactions in a quantum system drive the emergence of excitations with quantum numbers that are absent in the building blocks. Outstanding examples are excitations with charge e/3 in the fractional quantum Hall effect, solitons in one-dimensional conducting polymers and Majorana states in topological superconductors. Fractionalization is also predicted to manifest itself in low-dimensional quantum magnets, such as one-dimensional antiferromagnetic S = 1 chains. The fundamental features of this system are gapped excitations in the bulk and, remarkably, S = 1/2 edge states at the chain termini, leading to a four-fold degenerate ground state that reflects the underlying symmetry-protected topological order. This record contains data to support the result in a recent publication of ours where we use on-surface synthesis to fabricate one-dimensional spin chains that contain the S = 1 polycyclic aromatic hydrocarbon triangulene as the building block. Using scanning tunneling microscopy and spectroscopy at 4.5 K, we probe length-dependent magnetic excitations at the atomic scale in both open-ended and cyclic spin chains, and directly observe gapped spin excitations and fractional edge states therein. Exact diagonalization calculations provide conclusive evidence that the spin chains are described by the S = 1 bilinear-biquadratic Hamiltonian in the Haldane symmetry-protected topological phase. Our results open a bottom-up approach to study strongly correlated phases in purely organic materials, with the potential for the realization of measurement-based quantum computation.</dc:description>
  <dc:identifier>https://archive.materialscloud.org/record/2021.161</dc:identifier>
  <dc:identifier>doi:10.24435/materialscloud:e8-aq</dc:identifier>
  <dc:identifier>mcid:2021.161</dc:identifier>
  <dc:identifier>oai:materialscloud.org:929</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Materials Cloud</dc:publisher>
  <dc:rights>info:eu-repo/semantics/openAccess</dc:rights>
  <dc:rights>Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode</dc:rights>
  <dc:subject>spin chains</dc:subject>
  <dc:subject>nanographene</dc:subject>
  <dc:subject>fractionalization</dc:subject>
  <dc:subject>Graphene flagship</dc:subject>
  <dc:subject>MARVEL/DD3</dc:subject>
  <dc:subject>ERC</dc:subject>
  <dc:subject>CSCS</dc:subject>
  <dc:subject>H2020</dc:subject>
  <dc:subject>SNSF</dc:subject>
  <dc:title>Observation of fractional edge excitations in nanographene spin chains</dc:title>
  <dc:type>Dataset</dc:type>
</oai_dc:dc>