Magnetic and transport properties of low-dimensional oxi-borates

Abstract

Transition metal oxi-borates present a variety of interesting physical behavior associated with the presence of low-dimensional sub-units ( ribbons or walls) in their structure. When transition metal ions with incomplete shells and spin S= 1 2 occupy randomly the octahedral sites in the ribbons we observe the formation of a random singlet phase in these one-dimensional structures. The magnetic behavior of ribbons randomly occupied by transition ions of spin S=1 is also investigated. When the sub-units are walls, we observe the formation of independent magnetic sub-systems which order separately. Homo-metallic systems with mixed valence ions present different types of charge ordering depending on the relative strength of the electron–electron or electron–phonon interaction.