Synthesis of delafossite-derived phases, with La, Pr, Nd, Sm, and Eu, and observation of spin-gap-like behavior

Kazuyuki Isawa, Yuji Yaegashi, Motoharu Komatsu, Mitsugu Nagano, Shiroshi Sudo, Maarit Karppinen, Hisao Yamauchi

Research output: Contribution to journalArticleScientificpeer-review

45 Citations (Scopus)

Abstract

The structural and physical properties of layered cuprates of a (Formula presented) delafossite structure have been investigated for various rare-earth elements (Formula presented) Y, La, Pr, Nd, Sm, and Eu. An oxygen-rich delafossite-derived phase, (Formula presented) as previously reported by Cava et al. for (Formula presented) and La was found for all the other (Formula presented) presently studied. Each as-sintered (Formula presented) sample appeared to have a nearly stoichiometric oxygen content, but by thermal oxidation excess oxygen atoms corresponding to (Formula presented) per formula unit could be loaded into the lattices. Although electrical resistivity (ρ) of the oxygen-rich (Formula presented) samples exhibited semiconducting behavior at temperatures below 325 K a couple of samples showed anomalous temperature dependences in ρ at low temperatures. Unusual temperature dependence of magnetic susceptibility (χ), was observed for Ca-doped (Formula presented) samples, but not for the other (Formula presented) phases. If the Curie term was subtracted from the susceptibility of (Formula presented) the remaining part of χ decreased monotonically with decreasing temperature down to (Formula presented) and then leveled off with a finite value. Assuming that this finite value could be attributed to the Pauli paramagnetism of free carriers, the χ vs (Formula presented) characteristics were compared with those of other layered cuprates, such as (Formula presented) and (Formula presented) which have been reported to exhibit spin-gap behavior.

Original languageEnglish
Pages (from-to)3457-3466
Number of pages10
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume56
Issue number6
DOIs
Publication statusPublished - 1997
MoE publication typeA1 Journal article-refereed

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