Scaling spin–phonon and spin–spin interactions in magnetoelectric Gd1−xYxMnO3

• Crucial role of structural distortions induced by ion substitution.
• Tuning of magnetic interactions through ion substitution.
• Facing spin–phonon coupling and competitive exchange magnetic interactions.
• Scaling of spin–phonon and spin–spin mechanisms.

We present a systematic study of the structure and lattice dynamics at room temperature, and the phonon behavior at low temperatures in orthorhombic Gd1−xYxMnO3 manganites, with 0≤x≤0.4. Powder x-ray diffraction and Raman scattering at ambient conditions reveal that the Jahn–Teller distortion is composition-independent, while the Mn–O1–Mn bond angle increases by about 0.5° from x=0 to x=0.4. The spin–phonon coupling was ascertained from the relation between the renormalized wavenumber of the in-plane O2 stretching mode, associated with the spin–spin correlation function. The balance between competitive magnetic interactions is discussed based on the temperature dependence of the phonon frequency renormalization.

Wavenumber of the in-plane O2 stretching mode as a function of the spin–spin correlation function, for GdMnO3 (a), and Gd0.8Y0.2MnO3 (b).Figure optionsDownload as PowerPoint slide