{"title":"Magnetic Order Induced by the Cooperation of Valence and Structural Instabilities in Eu1−xCaxCo2P2","authors":"Kodai Moriyama, Kohei Yoshinaga, Ryoichiro Matsui, Chishiro Michioka, Hiroaki Ueda, Kazuyoshi Yoshimura","doi":"10.7566/jpsj.93.033702","DOIUrl":null,"url":null,"abstract":"Magnetism of layered compound Eu<sub>1−</sub><i><sub>x</sub></i>Ca<i><sub>x</sub></i>Co<sub>2</sub>P<sub>2</sub> was investigated by means of magnetization, specific heat, and electrical resistivity measurements. It is found that Eu undergoes a phase transition from a divalent state to a mixed-valence state of Eu<sup>2+</sup><i><sup>δ</sup></i> and Eu<sup>(3−</sup><i><sup>δ</sup></i><sup>′)+</sup> simultaneously with a structural transition from the uncollapsed tetragonal (ucT) phase to the collapsed tetragonal (cT) phase near <i>x</i> = 0.5. Whereas the compounds with the ucT structure exhibit antiferromagnetic ordering of Eu<sup>2+</sup> moments, those with the cT structure exhibit additional magnetic ordering of Co moments. The ordering temperature of Co moments is much higher than those in other <i>A</i>Co<sub>2</sub>P<sub>2</sub> systems with a divalent <i>A</i> cation. These results suggest that an electron-doping effect on Co 3<i>d</i> bands owing to the Eu valence transition stabilizes the magnetic ordering of Co moments.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"98 1","pages":""},"PeriodicalIF":1.5000,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the Physical Society of Japan","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.7566/jpsj.93.033702","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"PHYSICS, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Magnetism of layered compound Eu1−xCaxCo2P2 was investigated by means of magnetization, specific heat, and electrical resistivity measurements. It is found that Eu undergoes a phase transition from a divalent state to a mixed-valence state of Eu2+δ and Eu(3−δ′)+ simultaneously with a structural transition from the uncollapsed tetragonal (ucT) phase to the collapsed tetragonal (cT) phase near x = 0.5. Whereas the compounds with the ucT structure exhibit antiferromagnetic ordering of Eu2+ moments, those with the cT structure exhibit additional magnetic ordering of Co moments. The ordering temperature of Co moments is much higher than those in other ACo2P2 systems with a divalent A cation. These results suggest that an electron-doping effect on Co 3d bands owing to the Eu valence transition stabilizes the magnetic ordering of Co moments.
通过磁化、比热和电阻率测量,研究了层状化合物 Eu1-xCaxCo2P2 的磁性。研究发现,在 x = 0.5 附近,Eu 经历了从二价态到 Eu2+δ 和 Eu(3-δ′)+混合价态的相变,同时发生了从非塌缩四方(ucT)相到塌缩四方(cT)相的结构转变。具有 ucT 结构的化合物表现出 Eu2+ 矩的反铁磁排序,而具有 cT 结构的化合物则表现出 Co 矩的附加磁性排序。Co 矩的有序温度远高于其他含有二价 A 阳离子的 ACo2P2 系统。这些结果表明,Eu 价态转变对 Co 3d 带产生的电子掺杂效应稳定了 Co 矩的磁有序性。
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