Metamagnetic transitions associated with two antiferromagnetic phases of PrMn1−xSb2 and its magnetic phase diagram

Abstract

$\mathrm{Pr}{\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Sb}}_{2}$ exhibits two antiferromagnetic orders that are attributed to the two magnetic elements Mn and Pr. Both magnetic phases have an intriguing magnetic structure as the magnetic moments are tilted from the principal crystal axes, but the magnetic properties had not been studied in detail. We grew single crystals of $\mathrm{Pr}{\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Sb}}_{2}$ and measured the temperature and magnetic field dependencies of magnetization for different field directions. We found that both Mn and Pr moments undergo a metamagnetic transition at different temperatures and different field directions. A spin-flop transition was observed prior to the metamagnetic transition of the Mn sublattice when the magnetic field ($H$) was applied parallel to the crystallographic $a$ axis, but not for $H||[110]$, reflecting the magnetic anisotropy. The destruction of the antiferromagnetic order of the Mn sublattice via metamagnetic transition promoted the ordering of the Pr moments, indicating that the two antiferromagnetic phases are in competition. The magnetic phase diagrams determined from our measurements indicate that the present compound is strongly anisotropic and exhibits a far richer variety of magnetic states than the other compounds in the same material family $A\mathrm{Mn}{X}_{2}$ ($A$: alkaline earth or rare earth element; $X$: Sb or Bi).