Monte Carlo study of a geometrically frustrated rare-earth magnetic compound: SrGd2O4

Abstract

We study the low-temperature magnetic phase transitions and phase diagram of one member of the lanthanide family of frustrated compounds, ${\text{SrGd}}_{2}{\text{O}}_{4}$, using Monte Carlo simulation techniques. A detailed experimental study of two members of the ${\text{SrLn}}_{2}{\text{O}}_{4}$ family of compounds, ${\text{SrHo}}_{2}{\text{O}}_{4}$ and ${\text{SrGd}}_{2}{\text{O}}_{4}$, has recently been carried out by Young et al. [O. Young, Ph.D. thesis, University of Warwick, 2013; O. Young, G. Balakrishnan, M. R. Lees, and O. A. Petrenko, Phys. Rev. B 90, 094421 (2014)]. A phase diagram for ${\text{SrGd}}_{2}{\text{O}}_{4}$ was mapped out in the field-temperature ($H\ensuremath{-}T$) plane from magnetization, susceptibility, and specific-heat measurements and several ordered phases were identified. However, the detailed nature of these phases was not determined. We have used a model of classical Heisenberg spins to investigate the low-temperature behavior. Our simulation results qualitatively agree with the experimental findings. By collecting data from all measured thermodynamic quantities, a $H\ensuremath{-}T$ phase diagram is constructed. It reveals four separate regions of phases with unique magnetic ordering. We have identified the nature of the order in each of these phases.