Effects of Lu-doping on the magnetic behaviour and ordering of (Ho1−xLux)2Fe2Si2C

We have investigated the effects of Lu substitution on the magnetic behaviour and ordering of (Ho${}_{1-x}$Lu${}_x$)₂Fe₂Si₂C ($x$ = 0.32 and 0.46) by high-resolution neutron powder diffraction, magnetisation and specific heat over the temperature range 2 to 300 K. Our study has established that the antiferromagnetic (AFM) state is weakened upon Lu substitution and that the Néel temperature T${}_N$ shifts towards lower temperature with increasing Lu content. The replacement of the magnetic Ho${}^{3+}$ ion by the non-magnetic Lu${}^{3+}$ ion of smaller atomic radius, leads to a modification of the crystal field levels, as indicated by the specific heat measurements. Neutron diffraction data analysis reveals that the magnetic structure of undoped Ho₂Fe₂Si₂C, which exhibits a commensurate, antiferromagnetic ordering of the Ho sublattice along the $b$-axis with a propagation vector k = [0, 0, $\frac{1}{2}$], is maintained in the Lu-doped (Ho${}_{1-x}$Lu${}_x$)₂Fe₂Si₂C compounds.