Kagomé Spin Ice in the Presence of an External Magnetic Field

• Grant number: 25/10895-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Eric de Castro e Andrade
• Grantee: Elisa Torrecilha Costa Pinto
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/06629-4 - Electronic correlations in quantum materials: inhomogeneities and frustration, AP.JP2

Abstract

This project advances our systematic investigation into the magnetic behavior of frustrated systems, extending previous studies on the antiferromagnetic Ising model on a triangular lattice to the kagomé lattice. While conventional triangular lattices exhibit characteristic up-up-down magnetic ordering under an external field, the highly frustrated geometry of the kagomé lattice-- composed of corner-sharing triangles -- completely suppresses the possibility of long-range order, even under strong magnetic fields. In this project, we propose a detailed characterization of spin-spin correlation functions and ground-state entropy to elucidate the correlated and highly degenerate nature of this system. Subsequently, we will adopt a more realistic description of the problem, where spins are not constrained to align along a single global direction but may instead follow different local axes within each sublattice, similar to what is observed in magnetic pyrochlores, where strong spin-orbit interactions generate sufficient anisotropy to justify the use of the uniaxial spin approximation. We will also study the effects of a magnetic field on these Kagomé spin ices, systematically mapping the exotic states that emerge from the competition between local anisotropy and the external field. Our goal is to connect these findings with the phenomenology observed in materials such as HoAgGe and Fe¿Si¿Sn¿O¿¿, which are candidate systems for hosting this spin ice phase at zero field. (AU)