Characterizing thermomagnetic properties and crystal field excitations in rare-earth disordered pyrochlores candidates of strongly correlated ground states

• Grant number: 25/01609-6
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: August 01, 2025
• End date: July 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Rafael Sá de Freitas
• Grantee: Pedro Lucas Oliveira Silva
• Supervisor: Henrik Moodysson Ronnow
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
• Associated to the scholarship: 23/12679-0 - Structural disorder in new geometrically frustrated magnets candidates of Quantum Spin Liquid, BP.DD

Abstract

Experimental realization of quantum phases, such as the Quantum Spin Liquid, is today a central topic in condensed matter physics. Under this context, this project aims to investigate the role of disorder as a tuning parameter to achieve new strongly correlated magnetic ground states. The study will be performed on frustrated magnets of the pyrochlore family of compounds A2B2O7, where A3+ is a magnetic rare-earth ion and B4+ a transition metal ion, that possesses a well-established record of exotic magnetic behavior at low temperatures. Six hafnates A2Hf2O7 (A=Eu, Gd, Tb, Dy, Ho, Er), and one zirconate, Ho2Zr2O7, have already been synthesized. Structural characterization has shown that most of these compounds have a defect-fluorite structure. The characterization will be performed using both macroscopic and local probes of the spin dynamics and crystal electric field excitations, both properties that are significantly affected by quenched disorder. Only recently disorder has received close attention due to its implications on pyrochlores and is now recognized as a fundamental property to fully understand the exotic behaviors exhibited by these systems. We plan to study these materials systematically through bulk measurements including magnetic susceptibility and specific heat and also using local probes using neutron scattering techniques, an invaluable tool to study magnetic materials.