Pressure-induced modifications of the magnetic order in the spin-chain compound Ca3Co2O6

The structural and magnetic properties of the $\mathrm{C}{\mathrm{a}}_{3}\mathrm{C}{\mathrm{o}}_{2}{\mathrm{O}}_{6}$ spin-chain compound have been studied by means of neutron and x-ray powder diffraction at pressures up to 6.8 and 32 GPa, respectively. A suppression of the initial spin-density wave state $({T}_{\mathrm{N}}=25\phantom{\rule{0.28em}{0ex}}\mathrm{K})$ and stabilization of the collinear commensurate antiferromagnetic (AFM) state at high pressures $({T}_{\mathrm{NC}}=26\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ at $P=2.1$ GPa) were observed. The pressure behavior of the competing intra- and interchain magnetic interactions was analyzed on the basis of obtained structural data and their role in the formation of the magnetic phase diagram is discussed. The pressure behavior of the N\'eel temperature of the commensurate AFM phase was evaluated within the mean field theory approach and a good agreement with the experimental value $d{T}_{\mathrm{NC}}/dP=0.65\phantom{\rule{0.28em}{0ex}}\mathrm{K}/\mathrm{GPa}$ was obtained.