Spin order on the pyrochlore lattice: Magnetic crystallography, Landau thermodynamics and emergent phenomena

Pyrochlore sublattice is an integral structural component of numerous families of electronic and magnetic materials, including pyrochlores, spinels, and Laves phases C15, which exhibit plethora of magnetic behavior and multiple functionalities. The geometrical frustration inherent in the pyrochlore lattice leads to the formation of a broad diversity of unconventional magnetic states with unique physical properties. This article focuses on the symmetry-based concept of the Landau order parameter (OP) for uniform description of the most common types of long-range ordered magnetic structures (aristotypes) and related multi-ordered states derived from the pyrochlore lattice. Based on the combination of group-theoretical and crystallographic approaches the symmetry hierarchy of the magnetic structures and the corresponding OPs are established. The symmetry analysis reveals the role of the secondary OPs in the magnetic structure formation and emergent phenomena such as spin-driven ferroelasticity, ferroelectricity and orbital ordering. Within the framework of Landau thermodynamics, possible phase diagrams including multicritical points are determined. This study shows the significant potential of applying OP concept in a wide range of tasks, from the construction of microscopic theories to the search for new advanced magnetic and electronic materials.

Automated summary

This article explores the use of the Landau order parameter (OP) based on symmetry to describe the formation of spontaneous magnetic structures and related multi-ordered states. It also highlights the potential of this approach in the search for new advanced magnetic and electronic materials.