La3+ substitution effect on structural and magnetic properties of frustrated Ho2Ti2O7 pyrochlore

A renowned quantum material Ho2Ti2O7 in which structural and magnetic properties are coupled, is identified by its unusual spin freeze state. In the current report, magnetic and structural behaviour of Ho2-xLaxTi2O7 (x = 0.0, 0.1, and 0.2) pyrochlore prepared through solid state standard method, were investigated by partial replacement of Ho3+ with nonmagnetic La3+. The XRD along with Raman spectroscopy studies confirmed single phasic cubic pyrochlore structure with red and blue shift of the phonon mode and increase in the structural ordering due to increase in the ionic radii ratio by incorporation of La in Ho2-xLaxTi2O7. Cell parameter is also increased linearly with increasing La content and follow Vegard's rule. The crystalline size (71 +/- 5 nm, 87 +/- 6 nm and 107 +/- 5 nm for x = 0.0, 0.1 and 0.2, respectively) calculated from W-H plot is increased with nonmagnetic La doping which is consistent with electron microscopy studies. No spin glassy pattern was traced in magnetic studies even letting down the temperature up to 2 K. It was found that Curie Weiss temperature (theta(CW)) and effective magnetic moment (mu(eff)) shrinking with rising chemical pressure that leads to weakening of ferromagnetic character of the compounds. Observed shift in the energy barrier is explained on the basis of change in dipolar and exchange interaction which is responsible for the magnetic behaviour of Ho(2-x)La(x)Ti(2)O(7 )pyrochlore. Furthermore, reduction in the value of theta(CW) also depends upon the nature and location of the dopant. Large reduction in the e cw for Ho2Ti2O7 doped with La3+ suggested that doping at the A site can be used for the tuning the theta(CW). (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

By partially replacing Ho3+ with nonmagnetic La3+ in Ho2-xLaxTi2O7 compound, the magnetic and structural behavior was investigated. The study revealed that La doping induces structural ordering and increases the lattice parameter, while weakening the ferromagnetic properties of the compound.