Complex magnetic order in nickelate slabs

• DOI: 10.1038/s41567-018-0218-5
• Publication Date: 2018-07-19T15:34:48Z
• Authors: M. Hepting; R. J. Green; Z. Zhong; M. Bluschke; Y. E. Suyolcu; S. Macke; A. Frano; S. Catalano; M. Gibert; R. Sutarto; F. He; G. Cristiani; G. Logvenov; Y. Wang; P. A. van Aken; P. Hansmann; M. Le Tacon; J.-M. Triscone; G. A. Sawatzky; B. Keimer; E. Benckiser
• Keywords: Strongly Correlated Electrons (cond-mat.str-el); 530 Physics; Physics; ddc:530; General Physics and Astronomy; FOS: Physical sciences; 10192 Physics Institute; 530; 01 natural sciences; 3100 General Physics and Astronomy; Condensed Matter - Strongly Correlated Electrons; 0103 physical sciences; info:eu-repo/classification/ddc/530

Magnetic ordering phenomena have a profound influence on the macroscopic properties of correlated-electron materials, but their realistic prediction remains a formidable challenge. An archetypical example is the ternary nickel oxide system RNiO3 (R = rare earth), where the period-four magnetic order with proposals of collinear and non-collinear structures and the amplitude of magnetic moments on different Ni sublattices have been subjects of debate for decades. Here we introduce an elementary model system - NdNiO3 slabs embedded in a non-magnetic NdGaO3 matrix - and use polarized resonant x-ray scattering (RXS) to show that both collinear and non-collinear magnetic structures can be realized, depending on the slab thickness. The crossover between both spin structures is correctly predicted by density functional theory and can be qualitatively understood in a low-energy spin model. We further demonstrate that the amplitude ratio of magnetic moments in neighboring NiO6 octahedra can be accurately determined by RXS in combination with a correlated double cluster model. Targeted synthesis of model systems with controlled thickness and synergistic application of polarized RXS and ab-initio theory thus provide new perspectives for research on complex magnetism, in analogy to two-dimensional materials created by exfoliation.<br/>This is the accepted version of the manuscript. The revised manuscript according to peer reviews was published online in Nature Physics on July 23, 2018<br/>