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Dale R. Harshman John D. Dow W. J. Kossler D. R. Noakes C. E. Stronach A. J. Greer 《哲学杂志》2013,93(26):3055-3073
Muon spin rotation measurements are reported for GdSr2Cu2RuO8, a material with an onset temperature for superconductivity of about 45 K (which is virtually the same for its superconducting sister compounds Sr2YRu1? u Cu u O6 and Gd2? z Ce z Sr2Cu2RuO10). The data indicate two magnetic ordering transitions, at about 15 K and about 130 K, in addition to the Gd ordering transition known to occur at about 2.6 K. We tentatively attribute the 130 K transition to Ru and the 15 K transition to Cu ordering, effectively ruling out any superconducting mechanism based on fluctuating magnetic moments, which are frozen below about 15 K. If there is only one mechanism of high-temperature superconductivity, then the three facts that (i) all three sister compounds have essentially the same onset T c for superconductivity and (ii) all three of these compounds contain SrO layers but (iii) only two of the three compounds, GdSr2Cu2RuO8 and Gd2? z Ce z Sr2Cu2RuO10 (and not Sr2YRu1? u Cu u O6) contain cuprate planes imply that the superconducting layers of all three compounds must be the common SrO layers, and not the cuprate planes (which do not occur in Cu-doped Sr2YRuO6). Otherwise the coincidence of onset temperatures must be an accident, and there must be at least two mechanisms of high-T c superconductivity: one for doped Sr2YRuO6 and another for cuprate-plane superconductivity. 相似文献
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