Béron F, Soares G, Pirota K R
Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Rua Sergio Buarque de Holanda, 777, Cidade Universitária Zeferino Vaz, Campinas 13083-859, SP, Brazil.
Rev Sci Instrum. 2011 Jun;82(6):063904. doi: 10.1063/1.3600796.
We present a setup allowing to characterize the local irreversible behavior of soft magnetic samples. It is achieved by modifying a conventional ac induction magnetometer in order to measure first-order reversal curves (FORCs), a magnetostatic characterization technique. The required modifications were performed on a home-made setup allowing high precision measurement, with sensibility less than 0.005 Oe for the applied field and 10(-6) emu for the magnetization. The main crucial point for the FORCs accuracy is the constancy of the applied field sweep rate, because of the magnetic viscosity. Therefore, instead of the common way to work at constant frequency, each FORC is acquired at a slightly different frequency, in order to keep the field variation constant in time. The obtained results exhibit the consequences of magnetic viscosity, thus opening up the path of studying this phenomenon for soft magnetic materials.
