Chromium site selective substitution inCa3Co2O6: Influence on the magnetic properties of an Ising-like triangular lattice

D. Flahaut, A. Maignan, S. Hébert, C. Martin, R. Retoux, V. Hardy
2004 Physical Review B  
The structure of the Ca 3 Co 2 O 6 compound is made of chains on a triangular array. The intra-and interchain coupling are ferromagnetic and antiferromagnetic, respectively, and the chain itself contains a 1:1 alternation of CoO 6 trigonal prisms (TP) and octahedra (oct.). The Co 3+ spin states are high spin ͑S =2͒ and low spin ͑S =0͒ in the TP and the oct., respectively. It is found that a few percent of Cr 3+ ͑S =3/2͒ substituted for the low spin Co oct 3+ ͑S =0͒ greatly affect the magnetic
more » ... operties. Both coupling constants of the antiferromagnetic (interchain) and ferromagnetic (intrachain) interactions decrease as x increases up to x = 0.10 in Ca 3 Co 2−x Cr x O 6 . This is reflected by the decrease of the magnetization saturation and of the magnetic field characteristic of the ferri-to ferromagnetic transition, below the Néel temperature. These results are interpreted on the basis of an antiferromagnetic coupling between Co oct 3+ and its high spin Co TP 3+ neighbours. Furthermore, the magnetization jumps, observed below T Ͻ 10 K, tend to be suppressed on the isothermal magnetization curves as soon as x = 0.05. These results emphasize the great sensitivity of the Ca 3 Co 2 O 6 magnetic behavior to the presence of a magnetic foreign cation, with, in particular, a T N decrease probed by specific-heat measurements.
doi:10.1103/physrevb.70.094418 fatcat:vbxt7jkdu5hvzasfffax23syge