First-order magnetic phase transition in layered Sr3YCo4O10.5 + δ-type cobaltites

In layered Sr3YCo4O10.5 + δ-type cobaltites with different oxygen contents, we have observed a first order magnetic phase transition from the high-temperature “ferromagnetic” state to the low-temperature antiferromagnetic state. The transition can be induced by an applied magnetic field. It is accompanied by a significant hysteresis in the magnetic field (∼10 T) and temperature (∼10 K). A decrease and an increase in the yttrium content lead to a purely “ferromagnetic” and antiferromagnetic behavior, respectively.