Frustration-induced nanometre-scale inhomogeneity in a triangular antiferromagnet

• Published in: Nature communications Vol. 5; no. 1; p. 3222
• Main Authors: Zorko, A., Adamopoulos, O., Komelj, M., Arčon, D., Lappas, A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.01.2014; Nature Publishing Group; Nature Pub. Group
• Subjects: 140/131; 639/301/119/997; Electrons; Humanities and Social Sciences; multidisciplinary; NMR; Nuclear magnetic resonance; Phase transitions; Science; Science (multidisciplinary); Symmetry; Slovenia
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms4222

Phase inhomogeneity of otherwise chemically homogenous electronic systems is an essential ingredient leading to fascinating functional properties, such as high- T c superconductivity in cuprates, colossal magnetoresistance in manganites and giant electrostriction in relaxors. In these materials distinct phases compete and can coexist owing to intertwined ordered parameters. Charge degrees of freedom play a fundamental role, although phase-separated ground states have been envisioned theoretically also for pure spin systems with geometrical frustration that serves as a source of phase competition. Here we report a paradigmatic magnetostructurally inhomogenous ground state of the geometrically frustrated α-NaMnO 2 that stems from the system’s aspiration to remove magnetic degeneracy and is possible only due to the existence of near-degenerate crystal structures. Synchrotron X-ray diffraction, nuclear magnetic resonance and muon spin relaxation show that the spin configuration of a monoclinic phase is disrupted by magnetically short-range-ordered nanoscale triclinic regions, thus revealing a novel complex state of matter. The compound α-NaMnO 2 is very interesting due to the complexity of its phases, which are governed by different degrees of freedom. Here, the authors show that this compound possesses ground-state inhomogeneities due to geometrical frustration and simultaneously active spin and lattice degrees of freedom.