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

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.

arXiv comment7 pages, 3 figures, submitted to Europhysics Letters

References in corpus (5)

• Random Bonds and Topological Stability in Gapped Quantum Spin Chains
• Antiferromagnetic long-range order in Cu_{1-x}Zn_xGeO_3 with extremely low Zn concentration
• Coexistence of antiferromagnetism and dimerization in a disordered spin-Peierls model: exact results
• Impact of two mass-scale oscillations on the analysis of atmospheric and reactor neutrino data
• Slow relaxation experiments in disordered charge and spin density waves: collective dynamics of randomly distributed solitons

Cited by in corpus (5)

• Electronic crystals: an experimental overview
• Quantum critical point and superconducting dome in the pressure phase diagram of o-TaS3
• Energy relaxation in disordered charge and spin density waves
• Strongly disordered Hubbard model in one dimension: spin and orbital infinite randomness and Griffiths phases
• Generation of localized magnetic moments in the charge-density-wave state