L. Daroczi, Z. Balogh, L. Harasztosi, Z. Erdelyi, D. L. Beke, University of Debrecen, Debrecen, Hungary; T. A. Lograsso, Iowa State University, Ames, IA; T. L. Schlagel, Iowa State University, Ames Laboratory, IA
Different kinds of magnetic noise signals were studied in Ni2MnGa ferromagnetic shape memory alloy using an experimental set up developed at our department. The width (duration) and height (amplitude) distributions of the magnetic Barkhausen (MBN) signals in both austenite and martensite phases exhibit a power-law behavior for the duration and height. There are notable differences between the exponents of the austenitic and martensitic duration distributions, thus these phases belong to two different universality classes. The exponent of height distribution was obtained only for the martensite because of the very low noise level it was hardly detectable in austenite. The results are compared with the results of magnetic emission spectra obtained during the austenite/martensite transformation.
Summary: Magnetic Barkhausen (MBN) signals in both austenite and martensite phases exhibit power-law behavior for the duration and height distributions. The martensite and austenite phases can be considered as members of different universality classes characterized by different parameters of the noise distribution functions.
