Electronic structure study of new family of high-T c Fe-superconductors based on BaFe 2 As 2 in presence of dopants Rh a
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.409
Electronic structure study of new family of high-Tc Fe-superconductors based on BaFe2As2 in presence of dopants Rh and Pd. Ronald Columbié-Leyva1, Jacques Soullard2, Ilya G. Kaplan1* 1
Instituto de Investigación en Materiales, UNAM, AP 70-360, 04510, CDMX, Mexico.
2
Instituto de Física, UNAM, AP 20-364, 010000 CDMX, México.
Abstract
The superconductivity has a long history. One of the most recent discoveries is the superconductivity in the Fe- based family with anti- ferromagnetic state at ambient temperature. In this type of material, the transition to the superconductivity state was found in presence of different dopants. In this report we present the results of calculations of the cluster representing Ba4Fe5As8 in presence of Rh and Pd as dopants. The methodology of Embedded Cluster Method at the MP2 electron correlation level was employed. The population analysis showed two main features: the independence of charge density transfer from the spin density transfer and, the presence of orbitals with electron density but without spin density. The observed properties correspond to the RVB mechanism for the superconductivity transition proposed by Anderson for cuprates. This confirms our conclusions obtained in the same material doped by Co and Ni.
INTRODUCTION Iron pnictides are one of the last superconductors (SC) family of high- Tc that was recently in 2008 discovered [1, 2]. This family include six groups of iron-based compounds [3]. The mostly convenient studies are Ba-based 122 group, BaFe2As2. The pure compound is not SC, it is a paramagnetic semimetal. SC appears when it is doped by d-electrons atoms. SC phase in the 122 materials was first discovered by Co *
Corresponding author, [email protected]
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substitution of the Fe [4]. However, SC-phase is also occurred, if Ba or As are substituted by d-electron atoms. On the other hand, some d-electron atoms: Cr [5], Mo [6] Mn [7] and Cu [8,9] suppress the magnetism without stabilizing the high-Tc superconducting phase. To the best of our knowledge the reason for this is still unknown. Just after the discovery of the Fe- SCs, the DFT calculations revealed that all five 3d-orbitals of Fe are involved in the formation of the Fermi surfaces (FSs) [10, 11]. Three hole-FSs are located in the center of the Brillouin zone and two electron-FSs are located at the corner of the Brillouin zone. At present is well-known that Fe-SCs possess non-conventional SC, see [12, 13]. Calculations of the magnetic susceptibility [14] showed that these new SCs materials form antiferromagnetic order at zero doping. Fe-SCs belong to the broad category of strongly correlated superconductors such as heavy fermions and cuprates high-Tc SCs, although the latter have rather d
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