Electronic Phase Separation – Similar Features in Dissimilar Materials – Niels Bohr Institute - University of Copenhagen

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Electronic Phase Separation – Similar Features in Dissimilar Materials

Over recent years experimental reports of electronic inhomogeneity at varying length scales in materials with strong electron correlations have become increasingly common. Efforts to understand these variations have mostly proceeded in an ad-hoc, system by system manner. In this presentation I will describe electronic phase separation in two systems: a cuprate superconductor, superoxygenated La2-xSrxCuO4+y, and a cobaltate ferromagnet, SrCoO3-y. In both cases, adjusting the charge level by varying the oxygen concentration allows one to make compounds that exhibit coexistence of large separated regions with different electronic properties. In the former case there is a phase separation between antiferromagnetic and superconducting regions, [1,2] while in the latter between different ferromagnetic regions. [3] Despite being apparently quite different materials systems, aspects of their phase diagrams and some microscopic features of the phases present are remarkably similar. A comparison of these two systems might indicate common features of doped Mott insulator materials.

1. H. Mohottala et al., “Phase separation in superoxygenated La2-xSrxCuO4+y” Nature Materials 5, 377 (2006)
2. L. Udby et al., “Magnetic ordering in electronically phase-separated La2−xSrxCuO4+y: Neutron diffraction experiments” Phys. Rev. B 80, 014505 (2009)
3. C.K. Xie et al., “Magnetic phase separation in SrCoOx (2.5 ≤ x ≤ 3)” Appl. Phys. Lett. 99, 052503 (2011)

Talk by Barrett Wells, University of Connecticut, USA