Strong spin-orbit coupling and magnetic ordering in rare earth osmates with pyrochlore structure.

• Grant number: 25/15815-7
• Support Opportunities: Scholarships in Brazil - Master
• Start date: September 01, 2025
• End date: August 31, 2027
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Rafael Sá de Freitas
• Grantee: Walyson Otávio Soares dos Santos
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/12470-8 - Research in quantum materiais involving intense magnetic fields and low temperatures, AP.TEM

Abstract

The synthesis of rare-earth osmates with a pyrochlore structure (A2Os2O7, where A is a tetravalent rare-earth ion) enabled the study of the magnetic properties of the compounds Y2Os2O7 and Ho2Os2O7, based on the premise that these compounds constitute fertile ground for the manifestation of magnetism induced by the combined action of strong spin-orbit coupling and Hund coupling. In the first case, the ground state exhibits spin-glass behavior, the origin of which is not yet fully understood. In the second case, there are currently two distinct descriptions for the ground state: long-range magnetic ordering below 36 K and spin-ice behavior. In this context, the discrepancies between the descriptions, the small number of studies dedicated to these materials, and the feasibility of synthesizing other rare-earth osmates justify the need to analyze new compounds of this type. We propose the synthesis of A2Os2O7 samples (A = Dy, Er, Tb), in a single phase, the study of their crystallographic structures by X-ray diffraction and absorption and Raman spectroscopy, in addition to the analysis of the magnetic ground state through magnetization measurements and AC magnetic susceptibility at low temperatures.