Crystal field analysis of magnetic and optical properties of some rare earth and transition metal ions in pyrochlore compounds

Abstract

In recent decades, a large number of works have been performed on the magnetic and newlineoptical properties of rare-earth (RE) and transition metal (TM) ions in pyrochlore newlinecompounds, having general formula A 2 B 2 O 7 , where A is a rare-earth and B is usually a newlinetransition metal element. Both the A and B sites form a network of corner-sharing tetrahedra, newlineand hence, strong spin-frustration is profound in these systems. This frustration can issue a newlinelarge manifold of almost degenerate spin states at low temperatures, resulting in a delicate newlinebalance between the exchange and dipolar interactions, single-ion anisotropy, and hence the newlineunderlying geometry drives the system into diverse novel magnetic ground states. The newlinecrystal-field (CF) analysis plays an important role to study the above properties. newlineThe optical properties of TM ions (with 3d N electronic configuration) have been applied newlinein the different fields, such as, lighting, laser materials, optical data storage, luminescent and newlinefluorescent displays, etc. Because of the many practical applications, the optical properties of newline3d N have been investigated for a wide variety of host lattices. The practical use of 3d 3 ion- newlinedoped materials requires a better understanding of the relation between host lattice properties newlineand the optical properties of the TM ions. Mn 4+ ion in solid experiences a strong crystal-field newline(CF) of surrounding ligands due to its high effective positive charge. newline