Frustrated Magnetism and Cooperative Phase Transitions in Spinels

Abstract

The spinel crystal system, AB(2)O(4), has been fertile ground in studying the effects of magnetic and orbital frustration. The experimental findings, with primary focus on neutron and synchrotron x-ray scattering techniques, are hereby reviewed in spinels with magnetic B ions. Highlighted are novel collective phenomena, such as the zero-energy excitation mode in the spin liquid phase, zero-field and field-induced novel phase transitions, the emergence of complex local spin entities, and heavy fermionic behaviors. Such a diversity in the exotic properties stems from their close proximity to critical points among degenerate states and a delicate balance among different degrees of freedom such as spin, orbital, and lattice.