Structural Series in the Ternary A-Mn-As System (A = Alkali Metal): Double-Layer-Type CsMn4As3 and RbMn4As3 and Tunnel-Type KMn4As3
Structural Series in the Ternary A-Mn-As System (A = Alkali Metal): Double-Layer-Type CsMn4As3 and RbMn4As3 and Tunnel-Type KMn4As3
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DOI：
10.1021/acs.inorgchem.8b00018
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发表时间：
2018-05-07
影响因子：
4.6
通讯作者：
Hosono, Hideo
中科院分区：
文献类型：
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作者：
Ishida, Junichi;Iimura, Soshi;Hosono, Hideo
采用固相法合成了新型砷化锰化合物CsMn4As3、RbMn4As3和KMn4As3。它们由共享边的MnAs4四面体组成，这种四面体是类似于铁基超导体的积木。CsMn4As3和RbMn4As3采用KCu4S3型结构(四方P4/mmm空间群，第123号)，具有Mn4As3双层；而KMn4As3具有CaFe4As3型结构(正交Pnma空间群，第62号)，具有Mn4As3隧道骨架。从CsMn4As3和RbMn4As3到KMn4As3的结构变化以及其他三元A-Mn-As(A=碱金属)和AE-Mn-As(AE=碱土金属)化合物的结构趋势被理解为由于离子半径从Cs+减少到Mg2+，A和AE中心周围的配位数减少的结果。电阻率测量证实这三个新相为Mott绝缘体，禁带宽度分别为0.52(CsMn4As3)、0.43(RbMn4As3)和0.31 eV(KMn4As3)。磁测量和热容测量表明，CsMn4As3和RbMn4As3是反铁磁体，在400K以下没有明显的相变，这与LaMnAsO和BaMn2As2的磁性相似，而KMn4As3中存在铁磁成分，在179K时有磁相变。
New manganese arsenides CsMn4As3, RbMn4As3, and KMn4As3 were synthesized by solid-state reaction. They consist of edge-sharing MnAs4 tetrahedra, which are a building block similar to those of Fe-based superconductors. CsMn4As3 and RbMn4As3 adopt the KCu4S3-type structure (tetragonal P4/mmm space group, No. 123) with a Mn4As3 double layer, while KMn4As3 has the CaFe4As3-type structure (orthorhombic Pnma space group, No. 62) with a Mn4As3 tunnel framework. The structural change from CsMn4As3 and RbMn4As3 to KMn4As3 as well as the structural trend of the other ternary A-Mn-As (A = alkali metal) and AE-Mn-As (AE = alkaline-earth metal) compounds is understood as a consequence of reduction of the coordination number around the A and AE sites owing to the decrease of the ionic radius from Cs+ to Mg2+. Electrical resistivity measurements confirm that the three new phases are Mott insulators with band gaps of 0.52 (CsMn4As3), 0.43 (RbMn4As3), and 0.31 eV (KMn4As3). Magnetic and heat capacity measurements revealed that CsMn4As3 and RbMn4As3 are antiferromagnets without apparent phase transitions below 400 K, which is similar to the magnetism of LaMnAsO and BaMn2As2, while the existence of the ferromagnetic component was indicated in KMn4As3 with a magnetic transition at 179 K.