Magnetic properties of LaCo12B6 compound as probed by neutron diffraction and by magnetization study under high pressures

Abstract

The magnetic properties have been studied by magnetization measurements and the crystal and magnetic structure investigated by neutron diffraction. It is shown that LaCo12B6 compound exhibits an incommensurate conical type magnetic structure. Significantly different magnetic moments have been observed on the two Co crystal sites. The ambient pressure data are compared to that of YCo12B6 isotype and Landau coefficients have been derived from the magnetization curves for both compounds as well as their temperature dependence. The LaCo12B6 compound undergoes a transition from ordered to paramagnetic state at 160K. The volume dependence of intrinsic magnetic properties of the LaCo12B6 compound has been determined by studies under hydrostatic pressure up to 10kbar in temperature range 5–200K. Both the Curie temperature TC and the spontaneous magnetization MS decreases with increasing pressure. The observed decrease of MS with pressure (dMS/dp=−7.4×10−3μB/kbar at 5K) can be attributed to the pressure induced decrease of Co magnetic moments. The decrease of TC with pressure (dTC/dp=−0.49K/kbar) is comparable to the decrease observed on RCo12B6 compounds with non-magnetic R and can be attributed to the volume dependence of Co–Co exchange interactions. The remarkable role of the hybridization as a consequence of small distances between Co and B atoms could be a background of this rather unexpected volume stability of magnetic properties.