Metamagnetic Behavior of NdBaCo2O5 + δ, δ ≈ 0.5, Layered Cobaltite

NdBaCo2O5 + δ, $$\delta \approx 0.5$$ , layered cobaltite is a metamagnet, which at a relatively low magnetic field transforms below T ~ 20 K from the antiferromagnetic phase to the mixed ferromagnetic state. Above T ~ 20 K, it is a mixture of exchange-coupled ferromagnetic and antiferromagnetic phases. The transition from the quasimetallic state to the state with a low electrical conductivity is accompanied by the spin-state transition in Со3+ ions from the HS/LS state to the IS/LS one.