Unusual Magnetization Process And Magnetocaloric Effect In Alpha-Cov2o6 Driven By Pulsed Magnetic Fields

In low-dimensional Ising spin systems, an interesting observation is the presence of step magnetization at low temperatures. Here we combine both DC and pulsed magnetic fields to study the 1/3 magnetization plateau and multiple steps in the Ising spin-chain material alpha-CoV2O6. Magnetization in pulsed fields is quite different from that in DC fields, showing multiple steps in an intermediate range of 4.2-6 K, inverted hysteresis below 4.2 K and asymmetric magnetization in negative fields below 11 K. We demonstrate that these unusual behaviors in magnetization are caused by the spin dynamics and the anomalous magnetocaloric effect (MCE) in alpha-CoV2O6, i.e., abrupt changes of sample temperature in adiabatic conditions. We successfully separate the influence between the intrinsic slow spin dynamics and the quasi-extrinsic temperature change. From the MCE, we find that some irreversible behavior is originated from the slow spin dynamics. Two different slow dynamics associated with the metastable steps are observed: one is sensitive to the slow field sweep rate at the order of similar to mT s(-1) and weakly depends on temperature, while the other responds to the rapid field sweep rate of similar to kT s(-1) and dominates at lowest temperature. We also distinguish that the metastable transition at H (4) is the first order and crucial for the ferrimagnetic to ferromagnetic transition. This study is useful to the understanding of multistep magnetization in alpha-CoV2O6 and sheds light on recent experimental findings of related compounds.