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Autori: M Hagiwara, H Tsujii, C R Rotundu, B Andraka, Y Takano, T Suzuki, and S Suga
Editorial: Modern Physics Letters B, 21, No 16, p.965, 2007.
We review the results of specific-heat experiments on the S = 1 quasi-one-dimensional (quasi-1D) bond-alternating antiferromagnet Ni(C9H24N4)(NO2)ClO4, alias NTENP. At low temperatures above the transition temperature of a field-induced long-range order, the magnetic specific heat (Cmag) of this compound becomes proportional to temperature (T), when a magnetic field along the spin chains exceeds the critical field Hc at which the energy gap vanishes. The ratio Cmag/T, which increases as the magnetic field approaches Hc from above, is in good quantitative agreement with a prediction of conformal field theory combined with the field-dependent velocity of the excitations calculated by the Lanczos method. This result is the first conclusive evidence for a Tomonaga–Luttinger liquid in a gapped quasi-1D antiferromagnet.
Cuvinte cheie: Tomonaga–Luttinger liquid, one-dimensional S = 1 antiferromagnet, specific heat