ORALS

SESSION: ChemistryFriPM3-R9	Tressaud International Symposium on Solid State Chemistry for Applications and Sustainable Development
Fri Oct, 25 2019 / Room: Aphrodite A (100/Gr. F)
Session Chairs: Khalil Amine; Session Monitor: TBA

18:15: [ChemistryFriPM314]
Revisiting Crystal Structure - Hole Doping - Tc Relations in Overdoped M-1212 Superconducting Cuprates.
Miguel Angel Alario Franco¹ ; Sara Almudena Lopez Paz¹ ; Xabier Martinez De Irujo² ; ¹Inorganic Chemistry DPT.Facultad de Química Universidad Complutense, MADRID, Spain; ²Inorganic Chemistry DPT.Facultad de Química Universidad Complutensi, MADRID, Spain;
Paper Id: 61 [Abstract]

Among the factors controlling the critical temperature (Tc) in the high temperature superconducting cuprates (HTSC), the hole-doping level is one of the most crucial ones. In fact, superconductivity is suggested to be restricted to a “universal” hole doping level 1 psh comprised between ~0.06 and 0.31 holes per copper plane. While the complex charge-spin-lattice interplay in the underdoped regime (i.e. at p<popt) has attracted most of the efforts, the overdoped regime (p>popt) remains less explored and perceived as simpler, Fermi-liquid behaved. Recent results, however, are highlighting the potential of this overdoped region in the understanding of the condensation mechanism. In searching for overdoped systems, the so-called M-1212 phases resulting from partial or total substitution of copper in the Charge Reservoir Layer by other transition metals (TM) are suitable candidates. This is because they allow the total oxygen content to be widely modified with respect to the YSCO parent compound. This is particularly true for high valent TM, as the Mo(V-VI) and Fe(III-IV) cations in the Mo_0.3Cu_0.7Sr₂RECu₂Oy₃ and FeSr₂YCu₂Oy phases, in which the oxygen content can be raised to y > 7, above the YBCO limit. This leads to very highly doped CuO₂ planes, outside the Tc-psh paradigm. To shed light to the superconducting properties of these substantially overdoped (Mo & Fe)-1212 systems, we have varied both the oxidation degree and the RE size, looking at the effect of the crystal structure on Tc. We specifically focus on the connection between the atomic arrangement within the unit cell and the hole distribution. To that end, we have performed a joint structural-electronic characterization by means of NPD, ARM and EELS spectroscopy of ozone4 and high-pressure oxidized phases. We have observed that these materials, which are outside the paradigm, can be superconducting. Due to the Tc increasing with a whole doping level almost double than the above limit. We have also established the upmost importance of order-disorder in both the cation and anion sublattices.

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