Freezing of short-range ordered antiferromagnetic clusters in the CrFeTi${}_2$O${}_7$ system

Abstract

We report on the CrFeTi${}_2$O${}_7$ (CFTO) system using a combination of x-ray diffraction, dc magnetization, ac susceptibility, specific heat and neutron diffraction measurements. CFTO is seen to crystallize in a monoclinic $P21/a$ symmetry. It shows a glassy freezing at $T{}_f$ ~ 22 K, characterized by the observation of bifurcation between ZFC and FC $\ddot{I}‡$ (T) curves, frequency dispersion across $T{}_f$ in ac susceptibility, appearance of non-zero remanent magnetization and coercivity below $T{}_f$, very slow relaxation of iso-thermal remanent magnetization with time and a linear temperature dependence of magnetic contribution to specific heat $C{}_m$ below $T{}_f$. The microscopic neutron diffraction analysis of CFTO not only confirms the absence of long-range antiferromagnetic ordering but also exhibits diffuse scattering due to the presence of shortrange ordered antiferromagnetically correlated spin clusters.