Phys. Rev. Lett. 65, 3181–3184 (1990)Observation of S=1/2 degrees of freedom in an S=1 linear-chain Heisenberg antiferromagnetReceived 31 July 1990; published in the issue dated 17 December 1990 THe ground state of the typical spin-1 linear-chain Heisenberg antiferromagnet Ni(C2H8N2)2NO2(ClO4) containing a small amount of Cu2+ is studied by the electron-spin-resonance (ESR) technique. The ESR results are qualitatively explained by the model that the valence bonds are broken at the Cu2+ sites resulting in spin-1/2 states at the Ni2+ sites neighboring the Cu2+. Thus the present study gives experimental evidence for the existence of the valence-bond-solid ground state in S=1 linear-chain Heisenberg antiferromagnets. © 1990 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.65.3181
DOI:
10.1103/PhysRevLett.65.3181
PACS:
75.10.Jm, 75.30.Hx, 76.30.Fc
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