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

摘要: Below K, the pyrochlore orders into a noncollinear, antiferromagnetic structure referred to as the state. The magnetic order in 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 structure should be unstable to the formation of a related 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 with (pure), and 0.4 (), where magnetic is substituted by nonmagnetic . We find that the ground state of pure is significantly affected by magnetic dilution. The characteristic domain selection associated with the state, and the corresponding energy gap separating from , vanish for …