Raman study of the antiferromagnetic phase transitions in hexagonal Y MnO₃and LuMnO₃

Abstract

The A(1), E(1) and E(2) Raman active modes in hexagonal YMnO(3) and LuMnO(3) single crystals are studied as a function of temperature and compared with previous measurements. In addition to anharmonicity, some phonon frequencies show below T(N) anomalous temperature dependences that reflect the atomic displacements while some other phonon frequencies are more sensitive to the spin-phonon coupling.

Hexagonal Manganites—(RMnO3): Class (I) Multiferroics with Strong Coupling of Magnetism and Ferroelectricity

“…The study of magnetic and lattice excitations using inelastic neutron scattering experiments provided evidence for a strong coupling between magnons and phonons which appear to hybridize in one mixed elementary excitation [154], similar to the electromagnons studied in multiferroic orthorhombic manganites [161,162]. Raman and infrared absorption investigations of the temperature dependent phonon spectrum of YMnO 3 and LuMnO 3 have found a kink at and an abnormal hardening in the magnetically ordered phase, indicating strong spinphonon coupling [163][164][165]. Similar phonon hardening was also found in compounds with rare earth magnetic moments, HoMnO 3 and ErMnO 3 [128,166].…”

Study of crystal-field excitations and Raman active phonons in o-DyMnO3

“…The remaining absorption bands correspond to five out of seven Dy 3+ H 13/2 CF levels. The level frequencies, which are sensitive to the neighboring ligand locations, decrease due to anharmonicity between 100 and 300 K. They increase between 100 and 50 K by $ 1-8 cm À 1 , which is indicative of surrounding oxygen ions re-ordering that could explain the phonon softening in DyMnO 3 as observed in the case of the force constant renormalizations in YMnO 3 and LuMnO 3 [20].…”

Ultrafast dynamics of the Mn3+ d-d transition and spin-lattice interaction in YMnO3 film

“…Therefore, the understanding of the strong coupling among the charge, spin, orbital, and lattice degrees of freedom is a central topic of multiferroic oxide materials. Conventional studies of spin-lattice coupling in multiferroic oxides were investigated by steady-state spectroscopy, such as inelastic neutron scattering, 7 Raman spectra, 8 and thermal expansion measurements, 9 etc. In the last two decades, ultrafast optical spectroscopy has been demonstrated to provide valuable insights into the microscopic dynamics in materials as reported in Refs.…”