TY - JOUR
T1 - Spin gap and hole pairing of Sr14-xAxCu24O41(A = Ca and La) single crystals studied by the electrical resistivity and thermal conductivity
AU - Kudo, K.
AU - Ishikawa, S.
AU - Noji, T.
AU - Adachi, T.
AU - Koike, Y.
AU - Maki, K.
AU - Tsuji, S.
AU - Kumagai, K.
PY - 1999/12/1
Y1 - 1999/12/1
N2 - We have measured the electrical resistivity ρ and the thermal conductivity κ of Sr14-xAxCu24O41(A = Ca and La) single crystals. The Arrhenius plot of In ρ vs T-1 gives two kinds of activation energy with a boundary temperature Tρ. The activation energy at T < Tρ is in approximate agreement with the spin gap in the ladder estimated from the NMR measurements, suggesting that holes in the ladder are paired and localized at T < Tρ. The observed κ has been analyzed to be composed of κph, κspin and κhole due to phonons, spins and holes, respectively. The κph exhibits a small peak at ∼ 30 K in every direction of every single-crystal. The contribution of κspin is observed along the c-axis except for x(Ca) ≥ 6, and the spin gap, which corresponds to the spin excitation from spin-singlet to spin-triplet, has been estimated to be ∼ 420 K. For x(Ca) ≥ 6, the spin gap, which corresponds to the destruction of spin-singlet pairs i.e. the dissociation of hole pairs, has been estimated from κ along the c-axis at T > Tρ to decrease with increasing x(Ca).
AB - We have measured the electrical resistivity ρ and the thermal conductivity κ of Sr14-xAxCu24O41(A = Ca and La) single crystals. The Arrhenius plot of In ρ vs T-1 gives two kinds of activation energy with a boundary temperature Tρ. The activation energy at T < Tρ is in approximate agreement with the spin gap in the ladder estimated from the NMR measurements, suggesting that holes in the ladder are paired and localized at T < Tρ. The observed κ has been analyzed to be composed of κph, κspin and κhole due to phonons, spins and holes, respectively. The κph exhibits a small peak at ∼ 30 K in every direction of every single-crystal. The contribution of κspin is observed along the c-axis except for x(Ca) ≥ 6, and the spin gap, which corresponds to the spin excitation from spin-singlet to spin-triplet, has been estimated to be ∼ 420 K. For x(Ca) ≥ 6, the spin gap, which corresponds to the destruction of spin-singlet pairs i.e. the dissociation of hole pairs, has been estimated from κ along the c-axis at T > Tρ to decrease with increasing x(Ca).
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M3 - Article
AN - SCOPUS:0033318789
VL - 117
SP - 1689
EP - 1693
JO - Journal of Low Temperature Physics
JF - Journal of Low Temperature Physics
SN - 0022-2291
IS - 5-6
ER -