Effect of chemical pressure on the crystal electric field states of erbium pyrochlore magnets

We have carried out a systematic study of the crystal electric field excitations in the family of cubic pyrochlores Er2B2O7 with B=Ge, Ti, Pt, and Sn, using neutron spectroscopy. All members of this family are magnetic insulators based on 4f11Er3+ and nonmagnetic B4+. At sufficiently low temperatures, long-range antiferromagnetic order is observed in each of these Er2B2O7 pyrochlores. The different ionic sizes associated with different …