Field-Induced Magnetic Transitions in the One-Dimensional Compound Ca_<b>3</b>Co_<b>2</b>O_<b>6</b>

Abstract

Magnetization measurements on the one-dimensional oxide Ca 3 Co 2 O 6 having a triangular net of Co 2 O 6 chains have been carried out both in static and pulsed high magnetic fields. The M / H vs. T curve obeys the Curie-Weiss law at high temperatures. Below 25 K, however, M / H increases abruptly, and a plateau is observed at 1/3 of the full moment in the M - H curve, suggesting a ferrimagnetic state of the ferromagnetic chains due to the antiferromagnetic interchain interaction. At low H , this system is considered to be in a partially disordered antiferromagnetic state for 10 K< T <25 K and in a ferrimagnetic state below 10 K. The observed plateau in the M - H curve for T ≤5 K is broader than for 10 K≤ T ≤20 K, indicating spin freezing at lower temperatures. The results can be discussed in terms of the triangular Ising spin systems.