# Interplay between localized and itinerant d electrons in a frustrated metallic antiferromagnet, 2H-AgNiO2

## TL;DR

This study investigates the complex magnetic and electronic behavior of 2H-AgNiO2, a frustrated metallic antiferromagnet, under high magnetic fields, revealing field-induced transitions, Fermi surface reconstruction, and strong electron-spin fluctuation interactions.

## Contribution

It provides new insights into the interplay between localized and itinerant electrons in a frustrated magnetic system under extreme conditions.

## Key findings

- Cascade of magnetic field-induced transitions observed.
- Fermi surface reconstructed by magnetic order.
- Significant electron mass enhancement (~3) detected.

## Abstract

We report the electronic and magnetic behaviour of the frustrated triangular metallic antiferromagnet 2H-AgNiO2 in high magnetic fields (54 T) using thermodynamic and transport measurements. Here localized d electrons are arranged on an antiferromagnetic triangular lattice nested inside a honeycomb lattice with itinerant d electrons. When the magnetic field is along the easy axis we observe a cascade of field-induced transitions, attributed to the competition between easy-axis anisotropy, geometrical frustration and coupling of the localized and itinerant system. The quantum oscillations data suggest that the Fermi surface is reconstructed by the magnetic order but in high fields magnetic breakdown orbits are possible. The itinerant electrons are extremely sensitive to scattering by spin fluctuations and a significant mass enhancement (~ 3) is found.