Gapless spin excitations in nanographene-based antiferromagnetic spin-1/2 Heisenberg chains

• URL: http://arxiv.org/abs/2408.10045v1
• Date: Mon, 19 Aug 2024 14:36:33 GMT
• Title: Gapless spin excitations in nanographene-based antiferromagnetic spin-1/2 Heisenberg chains
• Authors: Chenxiao Zhao, Lin Yang, João C. G. Henriques, Mar Ferri-Cortés, Gonçalo Catarina, Carlo A. Pignedoli, Ji Ma, Xinliang Feng, Pascal Ruffieux, Joaquín Fernández-Rossier, Roman Fasel,
• Abstract summary: Haldane's seminal work established two fundamentally different types of excitation spectra for antiferromagnetic Heisenberg quantum spin chains. In finite-length half-integer spin chains, quantization induces a gap in the excitation spectrum, with the upper bound given by the Lieb-Schulz-Mattis (LSM) theorem. Here, we investigate the length-dependent excitations in spin-1/2 Heisenberg chains obtained by covalently linking olympicenes--Olympic rings shaped nanographenes carrying spin-1/2--into one-dimensional chains.
• Score: 8.1791518522452
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Haldane's seminal work established two fundamentally different types of excitation spectra for antiferromagnetic Heisenberg quantum spin chains: gapped excitations in integer-spin chains and gapless excitations in half-integer-spin chains. In finite-length half-integer spin chains, quantization, however, induces a gap in the excitation spectrum, with the upper bound given by the Lieb-Schulz-Mattis (LSM) theorem. Here, we investigate the length-dependent excitations in spin-1/2 Heisenberg chains obtained by covalently linking olympicenes--Olympic rings shaped nanographenes carrying spin-1/2--into one-dimensional chains. The large exchange interaction (J~38 mV) between olympicenes and the negligible magnetic anisotropy in these nanographenes make them an ideal platform for studying quantum spin excitations, which we directly measure using inelastic electron tunneling spectroscopy. We observe a power-law decay of the lowest excitation energy with increasing chain length L, remaining below the LSM boundary. In a long chain with L = 50, a nearly V-shaped excitation continuum is observed, reinforcing the system's gapless nature in the thermodynamic limit. Finally, we visualize the standing wave of a single spinon confined in odd-numbered chains using low-bias current maps. Our results provide compelling evidence for the realization of a one-dimensional analog of a gapless spin liquid.

Related papers

• Spin Squeezing with Magnetic Dipoles [37.93140485169168]
  Entanglement can improve the measurement precision of quantum sensors beyond the shot noise limit. We take advantage of the magnetic dipole-dipole interaction native to most neutral atoms to realize spin-squeezed states. We achieve 7.1 dB of metrologically useful squeezing using the finite-range spin exchange interactions in an erbium quantum gas microscope.
  arXiv  Detail & Related papers  (2024-11-11T18:42:13Z)
• Fabrication of Spin-1/2 Heisenberg Antiferromagnetic Chains via Combined On-surface Synthesis and Reduction for Spinon Detection [11.677646919977835]
  We report the fabrication of spin-1/2 Heisenberg chains through on-surface synthesis and in-situ reduction. A closed-shell nanographene is employed as a precursor for Ullman coupling to avoid radical fusing. The spin excitation gaps are found to decrease in power-law as the chain lengths, suggesting its gapless feature.
  arXiv  Detail & Related papers  (2024-08-16T15:24:09Z)
• Building spin-1/2 antiferromagnetic Heisenberg chains with diaza-nanographenes [12.13904791704878]
  Graphene nanostructures with pi-magnetism offer a chemically tunable platform to explore quantum magnetic interactions. We demonstrate the successful on-surface synthesis of spin-1/2 antiferromagnetic Heisenberg chains with parity-dependent magnetization. Our findings provide an effective strategy to construct nanographene spin chains and unveil the odd-even effect in their magnetic properties.
  arXiv  Detail & Related papers  (2024-07-30T02:58:33Z)
• Waveguide QED at the onset of spin-spin correlations [36.136619420474766]
  We find that molecules belonging to the crystal sublattice B form one-dimensional spin chains. The microwave transmission shows evidences for the collective coupling of quasi-identical spins to the propagating photons.
  arXiv  Detail & Related papers  (2024-04-04T18:00:05Z)
• Tunable topological phases in nanographene-based spin-1/2 alternating-exchange Heisenberg chains [8.1791518522452]
  We present a versatile platform enabling site-selective spin manipulation in many-body spin systems. Our findings are corroborated by theoretical calculations, opening promising avenues toward the development of spin-based quantum devices.
  arXiv  Detail & Related papers  (2024-02-21T07:45:05Z)
• Quantum spin chains with bond dissipation [0.26107298043931204]
  We study the effect of bond dissipation on the one-dimensional antiferromagnetic spin-$1/2$ Heisenberg model. Our results suggest that the critical properties of the dissipative system are the same as for the spin-Peierls model.
  arXiv  Detail & Related papers  (2023-10-17T18:46:27Z)
• Dynamics of magnetization at infinite temperature in a Heisenberg spin chain [105.07522062418397]
  In a chain of 46 superconducting qubits, we study the probability distribution, $P(mathcalM)$, of the magnetization transferred across the chain's center. The first two moments of $P(mathcalM)$ show superdiffusive behavior, a hallmark of KPZ. The third and fourth moments rule out the KPZ conjecture and allow for evaluating other theories.
  arXiv  Detail & Related papers  (2023-06-15T17:58:48Z)
• Emergence of non-Abelian SU(2) invariance in Abelian frustrated fermionic ladders [37.69303106863453]
  We consider a system of interacting spinless fermions on a two-leg triangular ladder with $pi/2$ magnetic flux per triangular plaquette. Microscopically, the system exhibits a U(1) symmetry corresponding to the conservation of total fermionic charge, and a discrete $mathbbZ$ symmetry. At the intersection of the three phases, the system features a critical point with an emergent SU(2) symmetry.
  arXiv  Detail & Related papers  (2023-05-11T15:57:27Z)
• Understanding the propagation of excitations in quantum spin chains with different kind of interactions [68.8204255655161]
  It is shown that the inhomogeneous chains are able to transfer excitations with near perfect fidelity. It is shown that both designed chains have in common a partially ordered spectrum and well localized eigenvectors.
  arXiv  Detail & Related papers  (2021-12-31T15:09:48Z)
• Quantum control of the tin-vacancy spin qubit in diamond [41.74498230885008]
  Group-IV color centers in diamond are a promising light-matter interface for quantum networking devices. The negatively charged tin-vacancy center (SnV) is particularly interesting, as its large spin-orbit coupling offers strong protection against phonon dephasing. We demonstrate multi-axis coherent control of the SnV spin qubit via an all-optical stimulated Raman drive.
  arXiv  Detail & Related papers  (2021-06-01T18:36:12Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.