Neutron diffraction and linear Grüneisen parameter studies of magnetism in NdFe2Ga8

Abstract

We study the magnetism in ${\mathrm{NdFe}}_{2}{\mathrm{Ga}}_{8}$ by the neutron-diffraction and temperature-modulated linear Gr\"uneisen parameter measurements. Previous thermodynamical measurements have demonstrated that there are two magnetic transitions at 10 and 14.5 K, respectively. Neutron-diffraction measurements confirm that the lower one is an antiferromagnetic (AFM) transition with a commensurate magnetic structure. Both the commensurate and the incommensurate (IC) magnetic peaks are found below the higher transition but their intensities only gradually increase with decreasing temperature. Below 10 K, the commensurate peak intensity increases quickly with decreasing temperature, signaling the AFM transition, while the IC peak intensity disappears below 5 K. The linear Gr\"uneisen parameter along the $c$ axis, ${\mathrm{\ensuremath{\Gamma}}}_{c}$, shows a hysteresis behavior that is different from the hysteresis behavior for the magnetization $M$. We give a discussion of the origin of the magnetism in ${\mathrm{NdFe}}_{2}{\mathrm{Ga}}_{8}$.