Fractional power-law susceptibility and specific heat in low temperature insulating state of o-TaS_{3}

K. Biljakovic; M. Miljak; D. Staresinic; J. C. Lasjaunias; P. Monceau; H. Berger; F. Levy

doi:10.1209/epl/i2003-00386-y

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Fractional power-law susceptibility and specific heat in low temperature insulating state of o-TaS_{3}

K. Biljakovic·M. Miljak·D. Staresinic·J. C. Lasjaunias·P. Monceau·H. Berger·F. Levy

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Abstract

Measurements of the magnetic susceptibility and its anisotropy in the quasi-one-dimensional system o-TaS_{3} in its low-T charge density wave (CDW) ground state are reported. Both sets of data reveal below 40 K an extra paramagnetic contribution obeying a power-law temperature dependence χ(T)=AT^{-0.7}. The fact that the extra term measured previously in specific heat in zero field, ascribed to low-energy CDW excitations, also follows a power law C_{LEE}(0,T)=CT^{0.3}, strongly revives the case of random exchange spin chains. Introduced impurities (0.5% Nb) only increase the amplitude C, but do not change essentially the exponent. Within the two-level system (TLS) model, we estimate from the amplitudes A and C that there is one TLS with a spin s=1/2 localized on the chain at the lattice site per cca 900 Ta atoms. We discuss the possibility that it is the charge frozen within a soliton-network below the glass transition T_{g}~40 K determined recently in this system.

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K. Biljakovic, M. Miljak, D. Staresinic, J. C. Lasjaunias, P. Monceau, H. Berger, F. Levy. 2002-10-17. Fractional power-law susceptibility and specific heat in low temperature insulating state of o-TaS_{3}. https://doi.org/10.1209/epl%2Fi2003-00386-y

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