Field-induced Incommensurate Lattice Modulations in the Delafossite CuFeO2

Abstract

The results of synchrotron X-ray diffraction measurements on a single crystal of the triangular lattice antiferromagnet CuFeO 2 under zero and non-zero applied magnetic fields are reported. We find four satellite reflections at (0, 3+ q , 1/2), (0, 4- q , 1/2), (0, 4-2 q , 0), and (0, 3+2 q , 0) with the incommensurate wave number q ∼0.415 in the ferroelectric incommensurate (FEIC) phase which appears in the magnetic field, H , between 7 and 13 T at low temperatures. In the partially disordered (PD) phase which exists in the temperature, T , range between 11 and 14 K, we find two satellite reflections at (0, 4- q , 1/2) and (0, 4-2 q , 0) with the incommensurate wave number q ∼0.4. The T and H dependence of these satellite reflections are studied. We interpret that the reflections observed in the FEIC phase arise from incommensurate lattice modulations caused by a magnetoelastic coupling with the underlying magnetic structure. The observation of the reflection (0, 4- q , 1/2) in finite fields and the (0, ...