Structural chemistry and metamagnetism of an homologous series of layered manganese oxysulfides
Structural chemistry and metamagnetism of an homologous series of layered manganese oxysulfides
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DOI：
10.1021/ja060892o
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发表时间：
2006-07-05
影响因子：
15
通讯作者：
Hadermann, Joke
中科院分区：
文献类型：
--
作者：
Gal, Zoltan A.;Rutt, Oliver J.;Hadermann, Joke
描述了一类具有超磁性质的层状氧化硫化物sr2mno2cu2m - δ Sm+1。Sr2MnO2Cu2-delta S2 （m) 1)、Sr2MnO2Cu4-delta S3 （m) 2）和Sr2MnO2Cu6-delta S4 (m) 3）是由Sr2+离子从变厚度的反萤石型硫化铜层中分离出的MnO2薄片组成。这三种化合物在铜硫化物层中都显示出大量相似的缺铜现象（δ接近0.5），单晶X射线和粉末中子衍射测量表明，m) 2和m) 3化合物中的铜离子在晶体学上是无序的，这与铜离子高二维迁移率的可能性一致。磁化率测量表明，该化合物具有高温居里-韦斯行为，其磁矩与高自旋锰离子一致，这些锰离子被氧化为（2+ δ）（+）态，以保持完整的Cu-3d/S-3p价带，并且该化合物是相应的p型半导体，在295 K时电阻率约为25 ω cm。正的魏斯温度表示矩间的净铁磁相互作用。因此，磁化率测量和低温粉末中子衍射测量表明，在零外加磁场下，MnO2片内的矩具有铁磁性耦合，而片间的反铁磁性耦合较弱，导致了a型反铁磁体。Sr2MnO2Cu5.5S4和Sr2MnO2Cu3.5S3是一种超磁体，分别在0.06和1.3 T的电场作用下，在25 K以下可以被驱动到完全有序的铁磁状态。讨论了这些化合物的组成、结构和物理性质之间的关系，以及化学控制这些性质的前景。
An homologous series of layered oxysulfides Sr2MnO2Cu2m-delta Sm+1 with metamagnetic properties is described. Sr2MnO2Cu2-delta S2 ( m) 1), Sr2MnO2Cu4-delta S3 ( m) 2) and Sr2MnO2Cu6-delta S4 ( m) 3), consist of MnO2 sheets separated from antifluorite-type copper sulfide layers of variable thickness by Sr2+ ions. All three compounds show substantial and similar copper deficiencies (delta approximate to 0.5) in the copper sulfide layers, and single-crystal X- ray and powder neutron diffraction measurements show that the copper ions in the m) 2 and m) 3 compounds are crystallographically disordered, consistent with the possibility of high two-dimensional copper ion mobility. Magnetic susceptibility measurements show high- temperature Curie-Weiss behavior with magnetic moments consistent with high spin manganese ions which have been oxidized to the ( 2+delta)(+) state in order to maintain a full Cu-3d/S-3p valence band, and the compounds are correspondingly p-type semiconductors with resistivities around 25 Omega cm at 295 K. Positive Weiss temperatures indicate net ferromagnetic interactions between moments. Accordingly, magnetic susceptibility measurements and low-temperature powder neutron diffraction measurements show that the moments within a MnO2 sheet couple ferromagnetically and that weaker antiferromagnetic coupling between sheets leads to A-type antiferromagnets in zero applied magnetic field. Sr2MnO2Cu5.5S4 and Sr2MnO2Cu3.5S3 are metamagnets which may be driven into the fully ordered ferromagnetic state below 25 K by the application of fields of 0.06 and 1.3 T respectively. The relationships between the compositions, structures, and physical properties of these compounds, and the prospects for chemical control of the properties, are discussed.