Schmehr Julian L, Zoghlin Eli, Porter Zach, Wang Xiaoping, Ruff Jacob P C, Tian Wei, Islam Zahirul, Wilson Stephen D
Materials Department, University of California, Santa Barbara, CA 93106, United States of America.
J Phys Condens Matter. 2019 Jun 19;31(24):244003. doi: 10.1088/1361-648X/ab0ef9. Epub 2019 Mar 12.
The breakdown of [Formula: see text] antiferromagnetism in the limit of strong disorder is studied in Sr(Ir Mn )O. Upon Mn-substitution, antiferromagnetic ordering of the Ir cations becomes increasingly two-dimensional, resulting in the complete suppression of long-range Ir magnetic order above [Formula: see text]. Long-range antiferromagnetism however persists on the Mn sites to higher Mn concentrations (x > 0.25) and is necessarily mediated via a random network of majority Ir sites. Our data suggest a shift in the Mn valence from Mn to Mn at intermediate doping levels, which in turn generates nonmagnetic Ir sites and suppresses long-range order within the Ir network. The collapse of long-range [Formula: see text] antiferromagnetism and the survival of percolating antiferromagnetic order on Mn-sites demonstrates a complex 3d-5d exchange process that surprisingly enables minority Mn spins to order far below the conventional percolation threshold for a bilayer square lattice.
