Low-Temperature Penetration Depth of κ − ( ET ) 2 Cu [ N ( CN ) 2</mml…
1999; American Physical Society; Volume: 83; Issue: 20 Linguagem: Inglês
10.1103/physrevlett.83.4172
ISSN1092-0145
AutoresA. Carrington, I. Bonalde, R. Prozorov, R. W. Giannetta, A. M. Kini, John A. Schlueter, H. H. Wang, U. Geiser, Jack M. Williams,
Tópico(s)Magnetism in coordination complexes
ResumoWe present high-precision measurements of the penetration depth of single crystals of $\ensuremath{\kappa}\ensuremath{-}(\mathrm{ET}{)}_{2}\mathrm{Cu}[\mathrm{N}(\mathrm{CN}{)}_{2}]\mathrm{Br}$ and $\ensuremath{\kappa}\ensuremath{-}(\mathrm{ET}{)}_{2}\mathrm{Cu}(\mathrm{NCS}{)}_{2}$ at temperatures down to 0.4 K. We find that, at low temperatures, the in-plane penetration depth $({\ensuremath{\lambda}}_{\ensuremath{\parallel}})$ varies as a fractional power law, ${\ensuremath{\lambda}}_{\ensuremath{\parallel}}\ensuremath{\sim}{T}^{\frac{3}{2}}$. While this may be taken as evidence for novel pair excitation processes, we show that the data are also consistent with a quasilinear variation of the superfluid density, as is expected for a $d$-wave superconductor with impurities or a small residual gap. Our data for the interplane penetration depth show similar features and give a direct measurement of the absolute value, ${\ensuremath{\lambda}}_{\ensuremath{\perp}}(0)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}100\ifmmode\pm\else\textpm\fi{}20\ensuremath{\mu}\mathrm{m}$.
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