invited by Cyrille BARRETEAU
Abstract :
CoV2O6 is currently at the center of an intense research activity due to its peculiar magnetic properties. It shows a very strong magnetocristalline anisotropy accompanied by a huge orbital contribution to its total magnetic moment (4.6 µB /Co ion instead of 3.0 µB for the spin S=3/2 only value). More interestingly, it exhibits a metamagnetic behaviour characterized by two steps in its magnetization curve for finite external fields, delimiting a plateau at 1/3 of the saturation magnetization in the absence of obvious triangular or kagome type lattice (Fig. 1(a)).
In this work, the electronic structure and magnetic properties of a-CoV2O6 are investigated using density functional theory calculations including spin-orbit coupling and orbital polarization effects.
These calculations reveal a strong magnetocristalline anisotropy with a magnetization easy axis close the c axis. Moreover, the evaluation of magnetic couplings (Fig. 1(b)) on the basis of broken-symmetry formalism suggests the occurrence of an antiferromagnetic ground-state order where ferromagnetic chains running along b are coupled antiferromagnetically to their nearest-neighbors along a and c.
Monte Carlo simulations are finally employed to explore the origins of the 1/3 plateau observed in the magnetization curves of this compound and to propose a structure for the corresponding state (Fig. 1(c)).
CINAM, Luminy