A sharp peak of the zero-temperature penetration depth at optimal composition in BaFe2(As1-xPx)2

K. Hashimoto, K. Cho, T. Shibauchi, S. Kasahara, Y. Mizukami, R. Katsumata, Y. Tsuruhara, T. Terashima, H. Ikeda, M. A. Tanatar, H. Kitano, N. Salovich, R. W. Giannetta, P. Walmsley, A. Carrington, R. Prozorov, Y. Matsuda

Research output: Contribution to journalArticlepeer-review

214 Citations (Scopus)


In a superconductor, the ratio of the carrier density, n, to its effective mass, m*, is a fundamental property directly reflecting the length scale of the superfluid flow, the London penetration depth, λL. In two-dimensional systems, this ratio n/m* (∼1/λL 2) determines the effective Fermi temperature, TF. We report a sharp peak in the x-dependence of λL at zero temperature in clean samples of BaFe2(As1-xP x)2 at the optimum composition x = 0.30, where the superconducting transition temperature Tc reaches a maximum of 30 kelvin. This structure may arise from quantum fluctuations associated with a quantum critical point. The ratio of Tc/TF at x = 0.30 is enhanced, implying a possible crossover toward the Bose-Einstein condensate limit driven by quantum criticality.

Original languageEnglish
Pages (from-to)1554-1557
Number of pages4
Issue number6088
Publication statusPublished - Jun 22 2012
Externally publishedYes

ASJC Scopus subject areas

  • General


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