Magnetic Phase Transition in AgCrO₂

Abstract

The magnetic ordering of AgCrO₂, a rhombohedrally stacked triangular-lattice antiferromagnet with Heisenberg spin S=3/2, has been studied by magnetic susceptibility measurement and neutron diffraction on a powder sample. The magnetic phase transition temperature was determined to be 24, K. The magnetic peaks appear at (0.327 {1em}0.327 {1em}0) in hexagonal units, which shows that the magnetic structure is a modulated 120° structure. The modulation is due to the competition between the intraplane and interplane interactions. The magnetic peaks are broad, indicating that this strong competition suppresses the development of the true long-range order in AgCrO₂ below 24, K.