Anomalous Long Time Tail Behavior of Spin-Spin Correlation in the Normal State of Tl 2 Ba 2 </mml:…
1994; American Physical Society; Volume: 73; Issue: 1 Linguagem: Inglês
10.1103/physrevlett.73.197
ISSN1092-0145
AutoresS. Kambe, Hiroshi Yaśuoka, Akihiko Hayashi, Yutaka Ueda,
Tópico(s)Advanced Condensed Matter Physics
ResumoWe have found a frequency ($\ensuremath{\omega}$) dependence of the spin-lattice relaxation time in the normal state of ${\mathrm{Tl}}_{2}$${\mathrm{Ba}}_{2}$Cu${\mathrm{O}}_{\mathrm{y}}$ (${T}_{c}=15$ and 85 K). The value of $\frac{1}{{T}_{1}T}$ at the Tl and Cu sites is proportional to ln ${\ensuremath{\omega}}^{\ensuremath{-}1}$ at low temperature. This type of $\ensuremath{\omega}$ dependence suggests a long time tail behavior of the spin-spin correlation. On the other hand, no frequency dependence is observed at the planar oxygen site; thus the observed long time tail behavior is enhanced around the wave vector $q=(\ensuremath{\pi},\ensuremath{\pi})$. The characteristic cutoff frequency for the long time tail decreases with decreasing $T$, indicating that the confinement of spin freedom occurs above ${T}_{c}$.
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