Structure, magnetic and dielectric properties in nano-crystalline Yb$_2$CoMnO$_6$

Structural, magnetic and dielectric properties have been studied for Yb$_2$CoMnO$_6$. Nano-crystalline sample of Yb$_2$CoMnO$_6$ synthesized by sol-gel method and structural analysis shows that the sample crystallizes in monoclinic crystal structure with \textit{P2$_1$/n} phase group. To understand the charge state of Co, Mn and Yb we have performed the XPS study. Magnetic study shows that the sample undergoes a paramagnetic to ferromagnetic phase transition around $T_c$ $\sim$56 K and an additional magnetic ordering at a lower temperature around 14 K due to ordering of Yb$^{3+}$ magnetic ions. Temperature dependent Raman study reveals that spin-phonon interaction is present in this material. Further, we have studied the dielectric properties of this material. We observed that the material shows a relaxation behavior that obeys the thermally activated relaxation mechanism. Impedance spectroscopy reveals that the material shows non-Debye's behavior. AC conductivity study is performed to understand the conduction mechanics which involve the quantum mechanical tunneling phenomenon.
Comment: 11 pages, 15 figures