Lattice and spin excitations in multiferroic h-YbMnO3

TL;DR

This study investigates lattice and spin excitations in hexagonal YbMnO3 using Raman scattering, revealing coupling between phonons and spin order, and the influence of Yb-Mn interactions on magnetic properties.

Contribution

It provides new insights into the coupling mechanisms between lattice vibrations and spin order in multiferroic YbMnO3, including effects of magnetic fields on spin excitations.

Findings

E2 phonon mode at 256 cm-1 couples to spin order

A1 phonon mode at 678 cm-1 softens at Neel temperature

Yb-Mn interactions significantly influence spin structure

Abstract

Lattice and spin excitations have been studied by Raman scattering in hexagonal YbMnO3 single crystals. The temperature dependences of the phonon modes show that the E2 mode at 256 cm-1 related to the displacement of Mn and O ions in a-b plane is coupled to the spin order. The A1 phonon mode at 678 cm-1 presents a soft mode behavior at the Neel temperature. Connected to the motion of the apical oxygen ions along the c direction, this mode controls directly the Mn-Mn interactions between adjacent Mn planes and the superexchange path. Crystal field and magnon mode excitations have been identified. The temperature investigation of the spin excitations shows that the spin structure is strongly influence by the Yb-Mn interaction. Under a magnetic field along the c axis, we have investigated the magnetic reordering and its impact on the spin excitations.