Helical magnetism and structural anomalies in triangular lattice {\alpha}-SrCr2O4

TL;DR

This study investigates the magnetic and structural properties of { extalpha}-SrCr2O4, revealing incommensurate helical magnetism, structural anomalies, and magneto-structural coupling in a frustrated triangular lattice system.

Contribution

It provides detailed neutron and synchrotron diffraction analysis showing helical magnetic order and structural anomalies linked to magneto-structural coupling in { extalpha}-SrCr2O4.

Findings

Incommensurate helical magnetic order with propagation vector k = (0,0.3217,0)

Increase in inter-plane spacing below 100 K

Structural anomalies at magnetic ordering temperature

Abstract

{\alpha}-SrCr2O4 has a triangular planar lattice of d3 Cr3+ made from edge sharing CrO6 octahedra; the plane shows a very small orthorhombic distortion from hexagonal symmetry. With a Weiss temperature of -596 K and a three-dimensional magnetic ordering temperature of 43 K, the magnetic system is quasi two-dimensional and frustrated. Neutron powder diffraction shows that the ordered state is an incommensurate helical magnet, with an in-plane propagation vector of k = (0,0.3217(8),0). Temperature dependent synchrotron powder diffraction characterization of the structure shows an increase in the inter-plane spacing on cooling below 100 K and an inflection in the cell parameters at the magnetic ordering temperature. These anomalies indicate the presence of a moderate degree of magneto-structural coupling.