Transistor Doping-Predictions for Superconductivity in the Charge Order Model

Abstract

Transistor doping of potential superconductors promises to illuminate inherent levels and limits for the materials in question. Here some of these limits are quantitatively predicted on a charge order or “radical” model for a variety of experiments. This model is based on a universal T _c scaling with anionic radical concentration. It is applicable to systems with covalently bonded, high electronegativity components. For the cuprates its general features are a linear increase of T _c with holes, which are normalized per total hole carrying species (e.g., O⁻ radical density). This dependence proceeds up to optima, corresponding to a uniform alternate hole charge order limit and T _c decreases thereafter with various slopes. The optima are quantitatively calibrated through the deleterious influence of the Blocking layer as measured by its O content. Amongst the predictions is a general limit of T _c ^max ∼ 167 K for oxide superconductors, obtainable in infinite layer type compounds (CaCuO₂). Other predictions are optimal T _c ∼ 83 K for La₂CuO₄ and maximum values potentially near 500 K for borides or carbides.