| I will present experimental data on single crystals of the frustrated triangular metallic antiferromagnet 2H-AgNiO2 in high magnetic fields (54T) using thermodynamic and transport measurements. The 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 sytem is a good metal and shows quantum oscillations. The Fermi surface is likely to be 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. |
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