Magnetic dilution of a honeycomb lattice XY magnet CoTiO₃

Abstract

We report our study of cobalt (II) titanate, CoTiO3, in which magnetic Co ions are replaced by non-magnetic ions. The antiferromagnetic ordering transition of CoTiO3 around 37 K is described with ferromagnetic honeycomb layers coupled antiferromagnetically along the crystallographic c direction. The effect of magnetic dilution on the Néel temperature of this material is investigated through the doping of Zn2+ and Mg2+ in place of Co2+ for various dilution levels up to x + y = 0.46 in Co1-x-yZnxMgyTiO3. Single phase polycrystalline samples have been synthesized and their structural and magnetic properties have been examined. A linear relation between dilution and the Néel temperature is observed over a wide doping range. A linear extrapolation would suggest that the required dilution level to suppress magnetic order is around x + y ∽ 0.74, well beyond the classical percolation threshold. The implication of this observation for microscopic models for describing CoTiO3 is discussed.

An intermediate phase induced by dilution in a correlated Dirac Fermi system

“…Magnetic dilution has been the subject of extensive research efforts in the context of percolation phenomena. The effect of dilution on magnetic order has received extensive attention for graphene-like materials [36,53]. In this paper, we focus on a Dirac fermion system with on-site interactions and study the effects of dilution on both the magnetic order and insulatormetal transition.…”

“…In CoTiO 3 , a linear relation between dilution and the critical temperature of magnetic transition is observed over a wide dilution range [36]. Under out-of-plane interactions or second-and third-nearest-neighbor exchange interactions, the long-range AFM order survives well past the classical percolation threshold x c = 0.3 [36][37][38]. Our study focuses on the magnetic phase transition caused by dilution in the system with on-site interaction, and it is also interesting to study whether magnetic order transition and metal-insulator transition take place concomitantly.…”

“…In related experiments, the honeycomb lattice provides a great platform to study dilution. In CoTiO 3 , a linear relation between dilution and the critical temperature of magnetic transition is observed over a wide dilution range [36]. Under out-of-plane interactions or second-and third-nearest-neighbor exchange interactions, the long-range AFM order survives well past the classical percolation threshold x c = 0.3 [36][37][38].…”