Magnetic dilution and domain selection in the XY pyrochlore antiferromagnet Er${}_2$Ti${}_2$O${}_7$

Abstract

Below $T_N=1.1$K, the XY pyrochlore Er${}_2$Ti${}_2$O${}_7$ orders into a $k=0$ non-collinear, antiferromagnetic structure referred to as the ${\psi }_2$ state. The magnetic order in Er${}_2$Ti${}_2$O${}_7$ is known to obey conventional three dimensional (3D) percolation in the presence of magnetic dilution, and in that sense is robust to disorder. Recently, however, two theoretical studies have predicted that the ${\psi }_2$ structure should be unstable to the formation of a related ${\psi }_3$ magnetic structure in the presence of magnetic vacancies. To investigate these theories, we have carried out systematic elastic and inelastic neutron scattering studies of three single crystals of Er${}_{2-x}$Y${}_x$Ti${}_2$O${}_7$ with $x=0$ (pure), 0.2 (10$\%$-Y) and 0.4 (20$\%$-Y), where magnetic Er${}^{3+}$ is substituted by non-magnetic Y${}^{3+}$. We find that the ${\psi }_2$ ground state of pure Er${}_2$Ti${}_2$O${}_7$ is significantly affected by magnetic dilution. The characteristic domain selection associated with the ${\psi }_2$ state, and the corresponding energy gap separating ${\psi }_2$ from ${\psi }_3$, vanish for Y${}^{3+}$ substitutions between 10$\%$-Y and 20$\%$-Y, far removed from the 3D percolation threshold of $\sim$60$\%$-Y. The resulting ground state for Er${}_2$Ti${}_2$O${}_7$ with magnetic dilutions from 20$\%$-Y up to the percolation threshold is naturally interpreted as a frozen mosaic of ${\psi }_2$ and ${\psi }_3$ domains.

8 pages,7 figures, 1 table

References in corpus (10)

• Definitive Evidence for Order-by-Quantum-Disorder in Er2Ti2O7
• Quantum order by disorder and accidental soft mode Er2Ti2O7
• Lightly stuffed pyrochlore structure of single-crystalline Yb2Ti2O7 grown by the optical floating zone technique
• Is the Yb2Ti2O7 pyrochlore a quantum spin ice?
• Energetic selection of ordered states in a model of the Er2Ti2O7 frustrated pyrochlore XY antiferromagnet
• Magnetic order, magnetic correlations and spin dynamics in the pyrochlore antiferromagnet Er2Ti2O7
• Order by Disorder and Energetic Selection of the Ground State in the XY Pyrochlore Antiferromagnet Er2Ti2O7. An Inelastic Neutron Scattering Study
• Order from structural disorder in $XY$ pyrochlore antiferromagnet $\mathrm{E}{\mathrm{r}}_2\mathrm{T}{\mathrm{i}}_2{\mathrm{O}}_7$
• Order-by-disorder near criticality in $XY$ pyrochlore magnets
• Order Induced by Dilution in Pyrochlore XY Antiferromagnets

Cited by in corpus (4)

• Effect of Chemical Pressure on the Crystal Electric Field States of Erbium Pyrochlore Magnets
• Experimental evidence for field induced emergent clock anisotropies in the XY pyrochlore Er${}_2$Ti${}_2$O${}_7$
• Doping-induced quantum cross-over in Er${}_2$Ti${}_{2-x}$Sn${}_x$O${}_7$
• Absence of long-range order in an $XY$ pyrochlore antiferromagnet Er${}_2$AlSbO${}_7$