Quasi-two-dimensional ferromagnetism in the triangular magnet EuAl${}_{12}$O${}_{19}$

Abstract

We report ferromagnetic ordering at $T_{\mathrm{C}}=1.3$K in the quasi-two dimensional magnet EuAl${}_{12}$O${}_{19}$ with large spins $S=7/2$. This ferromagnetic state was characterized by magnetization and specific heat measurements and the experimental results were compared with classical Monte Carlo simulations. They reveal a strong single ion anisotropy leading to an uniaxial spontaneous magnetization along the $c$ axis. Furthermore the application of a magnetic field in the hard magnetization plane $ab$ reduces the Curie temperature and it reaches zero temperature at a magnetic field of $\hat{I}{¼}_0{H}_c\approx 0.5$T.