Coupled spin waves and crystalline electric field levels in candidate multiferroic ErFeO3

Abstract

We report an inelastic neutron scattering study of candidate multiferroic com.elsevier.xml.ani.Math@721eb7ed, a compound that has been previously reported to have three different magnetic states and undergoes signatures of com.elsevier.xml.ani.Math@751fb851 cooperative coupling. The spectrum at low energy transfer is dominated by excitations of the com.elsevier.xml.ani.Math@f83b47f character, even above the com.elsevier.xml.ani.Math@14570514 antiferromagnetic ordering temperature of 4.5 K. In addition, a crystalline electric field excitation at 6 meV exhibits additional energy splitting upon cooling through 4.5 K with mode-dependent polarization. This indicates different moment directions for these modes, an interesting consequence of com.elsevier.xml.ani.Math@137179ac ordering of the com.elsevier.xml.ani.Math@1ba486a3 moments.