Molecular Metals Based on BEDT‐TTF Radical Cation Salts with Magnetic Metal Oxalates as Counterions: β″‐(BEDT‐TTF)4A[M(C2O4)3]·DMF (A = NH4+, K+; M = CrIII, FeIII)
Molecular Metals Based on BEDT‐TTF Radical Cation Salts with Magnetic Metal Oxalates as Counterions: β″‐(BEDT‐TTF)4A[M(C2O4)3]·DMF (A = NH4+, K+; M = CrIII, FeIII)
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基于 BEDT-TTF 自由基阳离子盐和磁性金属草酸盐作为抗衡离子的分子金属：β″-(BEDT-TTF)4A[M(C2O4)3]·DMF (A = NH4+, K+; M = CrIII, FeIII)
DOI：
10.1002/adfm.200304283
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发表时间：
2003
影响因子：
19
通讯作者：
E. Yagubskii
中科院分区：
文献类型：
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作者：
T. Prokhorova;S. Khasanov;L. Zorina;L. Buravov;V. Tkacheva;A. Baskakov;R. Morgunov;M. Gener;E. Canadell;R. Shibaeva;E. Yagubskii
用电结晶法制备了四种(BEDT-TTf)4A[M(C2O4)3]·DMF(DMF=二甲基甲酰胺)盐，其中A = (NH4，K)，M = Cr(1)；A = NH4，M = Fe(2)；A = K，M = Cr(3)；A = NH4，M = Cr(3‘)。用单晶X射线衍射法、电子自旋共振(ESR)谱、电阻测量和电子能带结构计算对这些盐进行了表征。这些结构(C2/c空间群)由交替的β“型层状结构和A+离子与金属形成的近似六方网络组成，其中溶剂分子DMF占据阴离子层中的六方空穴。所有的盐都是低至4.2K的二维有机金属，不表现出超导电性。它们的电子能带结构类似于已知的有机超导体β“-(BEDT-TTf)4H3O[Fe(C2O4)3]·BN。盐1和3‘的ESR谱表现为两种共振，一种是由Cr3+的三维定域电子引起的高斯型共振，另一种是由有机层中的传导电子引起的洛伦兹(和戴森)型共振。在计算的费米面的基础上，提出如果无序不妨碍观察到Shubnikov-de Haas振荡，这些盐可能表现出有趣的磁阻行为。
Four (BEDT‐TTF)4A[M(C2O4)3]·DMF (DMF = dimethylformamide) salts of the organic donor molecule bis(ethylenedithio)tetrathiafulvalene (BEDT‐TTF) with metal oxalate anions, where A = (NH4, K), M = Cr (1); A = NH4, M = Fe (2); A = K, M = Cr (3); and A = NH4, M = Cr (3′) were prepared by electrocrystallization. These salts were characterized by single‐crystal X‐ray diffraction, electron spin resonance (ESR) spectroscopy, electrical resistance measurements, and electronic band structure calculations. The structures (with space group C2/c) consist of alternating β″‐type layers of BEDT‐TTF and an approximately hexagonal network formed by the A+ cation and the metal, with the solvent molecule, DMF, occupying hexagonal cavities in the anion layer. All of the salts are two‐dimensional organic metals down to 4.2 K and do not exhibit superconductivity. Their electronic band structure is similar to that of the known organic superconductor β″‐(BEDT‐TTF)4H3O[Fe(C2O4)3]·BN. The ESR spectra of salts 1 and 3′ are characterized by two resonances, one of Gaussian shape arising from the 3d localized electrons of Cr3+ and the other of Lorentzian (and Dysonian) shape due to the conduction electrons in the organic layers. On the basis of the calculated Fermi surfaces it is suggested that these salts could exhibit an interesting magnetoresistance behavior if disorder does not prevent the observation of the Shubnikov‐de Haas oscillations.