Low temperature magnetic behavior and thermal expansion anomaly of cubic CeTiO3.

Lanthanum-based LnBO3 perovskite oxides have demonstrated fascinating magnetic properties and spin-lattice coupling. In this work, we report an unusual thermal expansion anomaly coupled with the magnetic ordering in the cubic CeTiO3 with the vacancy of Ce ions. The magnetic behaviors and lattice thermal expansion at low temperature were systematically investigated using the temperature dependence of the magnetization measurements and low temperature X-ray powder diffraction. It is clearly revealed that there are two magnetic transitions in the cubic CeTiO3 from 5 to 350 K: one is a magnetic ordering-disordering transition at 300 K and the other one might be a change of the magnetic component near 32 K. Both the magnetization and hysteresis change correspondingly upon cooling. Intriguingly, a lattice thermal expansion anomaly is found below the magnetic ordering temperature, which indicates a strong coupling of spin and lattice, i.e., a magnetovolume effect (MVE). Our findings provide the possibility of adjusting thermal expansion behavior and magnetic properties by introducing a vacancy of Ln atoms in lanthanum-based perovskite oxides.