We have performed a detailed temperature-dependent study of optical f-f transitions of the $\mathrm{Y}{\mathrm{b}}^{3+}$ ions in $h-{\mathrm{YbMnO}}_3$ by means of Fourier-transform spectroscopy. The splitting of the ground Kramers doublet as a function of temperature, ${\mathrm{\Delta }}_0\left(T\right)$, was determined for the $\mathrm{Y}{\mathrm{b}}^{3+}$ ion at the $4b$ site. The ${\mathrm{\Delta }}_0\left(T\right)$ function follows the dynamics of the manganese magnetic moment below $T_N=87$ 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 the low-temperature dynamics of the $h\text{−}{\mathrm{YbMnO}}_3$ crystal. Using the ${\mathrm{\Delta }}_0\left(T\right)$ function, we calculated the temperature behavior of the $\mathrm{Yb}(4b$) magnetic moment: it is in clear agreement with the neutron data [S. Chattopadhyay et al., Phys. Rev. B 98, 134413 (2018)]. The calculated contribution of $\mathrm{Yb}(4b$) to heat capacity definitely explains the origin of the Schottky anomaly in the $C$($T$) dependence. A scenario for phase transitions in $h\text{−}{\mathrm{YbMnO}}_3$ is proposed, in which the energy gain in the ytterbium system plays a key role. A phase transition at 3.5 K is interpreted as spin reorientation.

Close

PrevNext

View figure in article

• Exchange interaction
• Magnetic order
• Multiferroics
• Fourier transform infrared spectroscopy