The ground ytterbium doublet in h-YbMnO3 and the related low-temperature peculiarities of the compound

TL;DR

This study investigates the temperature-dependent optical properties of Yb3+ ions in h-YbMnO3, revealing how the ytterbium subsystem interacts with manganese magnetism and influences low-temperature phase transitions.

Contribution

It provides detailed measurements of the Yb3+ ground doublet splitting and models its magnetic behavior, linking optical data with magnetic and thermodynamic properties.

Findings

The ground doublet splitting D0(T) follows manganese magnetic order below 87 K.

Yb subsystem is magnetized by manganese magnetic field, affecting low-temperature dynamics.

Yb contribution explains the Schottky anomaly and influences phase transition scenarios.

Abstract

We have performed detailed temperature-dependent study of optical f-f transitions of the Yb3+ ions in h-YbMnO3 by means of Fourier-transform spectroscopy. The splitting of the ground Kramers doublet as a function of temperature, D0(T), for the Yb3+ ion at 4b site was determined. The D0(T) function follows the dynamics of the manganese magnetic moment below TN = 87 K, indicating, that the ytterbium subsystem is magnetized by the magnetic field generated by an ordered manganese subsystem, which is consistent with the results of previous studies. Excitation of the upper component of the split ground doublet plays a significant role in low-temperature dynamics of the h-YbMnO3 crystal. Using the D0(T) function we calculated the temperature behavior of the of the Yb(4b) magnetic moment: it is in clear agreement with the neutron data [Phys. Rev. B 98, 134413, 2018]. The calculated contribution of Yb(4b) to heat capacity definitely explains the origin of the Schottky anomaly in the CP(T) dependence. A scenario for phase transitions in h-YbMnO3 is proposed in which the energy gain in the ytterbium system plays a key role.