José Lorenzana1 Jakub Gawraczynski2 3 Dominik Kurzydlowski2 4 Krzysztof Bienkowski2 Wojciech Gadomski3 Zoran Mazej5 Tomasz Jaron2 Andrzej Ozarowski8 Steve Hill8 9 Piotr Leszczynski2 Kamil Tokár7 Mariana Derzsi2 Paolo Barone6 Wojciech Grochala2

1, Istituto dei Sistemi Complessi-CNR, Roma, , Italy
2, University of Warsaw, Warsaw, , Poland
3, University of Warsaw, Warsaw, , Poland
4, Cardinal Stefan Wyszynski University in Warsaw, Warsaw, , Poland
5, Department of Inorganic Chemistry and Technology, Ljubljana, , Slovenia
8, Florida State University, Tallahassee, Florida, United States
9, Florida State University, Tallahassee, Florida, United States
7, Institute of Physics, Slovak Academy of Sciences, Bratislava, , Slovakia
6, CNR-SPIN c/o Università dell’Aquila, L'Aquila, , Italy

The parent compound of high-Tc superconducting cuprates is a unique Mott state consisting of layers of spin-1 / 2 ions arranged on a square lattice, with a record high antiferromagnetic coupling within the layers, strong covalency between transition metal (TM) and ligands and no orbital degeneracy. There have been several attempts to replicate these characteristics with different TM ions. One proposal has been to use nickel(I) in place of copper(II). LaNiO2 is isoelectronic and isostructural with infinite layer parent cuprates, however, it lacks the strong covalent character between TM and ligand and the antiferromagnetic order has not been found. Sr2IrO4 has many similarities with cuprates including a robust antiferromagnetic order of spin-1/2 pseudospins. However, the correlated insulator character is much weaker and spin-orbit coupling effects dominate. I will discuss an alternative route where, to a large extent, these problems are solved and the physics of Cu(II) ions emerges without Cu.