Probing the tunability of magnetism with external pressure in metastable Sr2NiIrO6 double perovskite

In Sr2NiIrO6 long-range Jr-Ir antiferromagnetic exchange interactions have been reported to overcome the ferromagnetic Ni-Ir interactions hampering the otherwise expected ferromagnetic behavior. Prompted by this, a combination of x-ray absorption spectroscopy and x-ray diffraction at high pressure is used here to investigate the interplay between the magnetic structure of the Jr sublattice and lattice degrees of freedom. The compression of Sr(2)NiIrO(6 )drives an unexpected nonmonotonic change of the x-ray magnetic circular dichroism (XMCD) spectra: The intensity first decreases in the 0- to 18-GPa range, then shows an increase in the 18- to 30-GPa range and again decreases for higher pressures. The XMCD intensity, a measure of the net magnetization in the Jr sublattice, however, is found to remain very low in the whole pressure range so the observed changes do not correspond with a transition from antiferromagnetic to ferromagnetic or ferrimagnetic order. The evolution of the XMCD is better explained in terms of a weakening/strengthening of the long-range antiferromagnetic (AFM) JrJr interaction between ferromagnetic planes associated with the reduction of the lattice parameters. In particular, a correlation can be established between the evolution of the b/a ratio and the weakening/strengthening of the AFM interaction.

Automated summary

This study investigates the interplay between the magnetic structure of Sr2NiIrO6 and lattice degrees of freedom under high pressure using x-ray absorption spectroscopy and x-ray diffraction. The results show non-monotonic changes in the x-ray magnetic circular dichroism spectrum with increasing pressure, indicating that the observed changes are not a transition from antiferromagnetic to ferromagnetic order. Instead, the changes can be better explained by the weakening/strengthening of the long-range antiferromagnetic interaction between the Jr sublattice planes associated with the reduction of the lattice parameters.