Magnetic hysteresis in the Cu-Al-Mn intermetallic alloy: Experiments and modeling

Abstract

We study isothermal magnetization processes in the Cu-Al-Mn intermetallic alloy. Hysteresis is observed at temperatures below the spin-freezing of the system. The characteristics of the hysteresis cycles as a function of temperature and Mn content ͑magnetic element͒ are obtained. At low temperature (Շ5 K͒ a change from smooth to sharp cycles is observed with increasing Mn content, which is related to the decrease of configurational disorder. We also study a zero-temperature site-diluted Ising model, suitable for the description of this Cu-Al-Mn system. The model reproduces the main features of the hysteresis loops observed experimentally. It exhibits a disorder-induced critical line separating a disordered phase from an incipient ferromagnetic ground state. The comparison between the model and the experiments allows us to conclude that the observed change in the experimental hysteresis loops can be understood within the framework of the theory of disorder-induced criticality in fluctuationless first-order phase transitions. ͓S0163-1829͑99͒13821-9͔

Hysteresis and avalanches in the random anisotropy Ising model

“…The mathematical conditions for such a property to occur have been discussed for the RFIM, 7 the RBIM, 3 and the SDIM. 10 The two RAIM models (A and B) studied in this work do not exhibit such a property, except for those situations in which no effective antiferromagnetic interactions occur. Figure 7 shows an example of internal loops revealing the failure of the RPM property.…”

“…Figure 12 displays the behavior of ͗s max /L 3 ͘ as a function of 0 for different system sizes. Data corresponds to averages over 50,200,300,500, and 300 different realizations of the disorder for Lϭ40, 30,20,10, and 6, respectively. The ͑pseudo͒ phase transition for the finite system will correspond to the inflection point of such curves.…”

“…A number of recent results point, however, in this direction. 10,12 In magnetic materials, a physically relevant source of disorder arises from the randomness of the magnetocrystalline anisotropy. This paper is aimed at analyzing the intrinsic zero-temperature hysteresis and avalanche properties in systems with such disorder.…”

Two-dimensional model for ferromagnetic martensites

“…We also find that the magnetic order influences the strain and vice versa substantially. We also study the 'noise' associated magnetic hysteresis [35,36,37] that is similar to Barkhausen noise.…”

Magnetic phase separation in ordered alloys

“…29 Such different magnetic behavior may be understood in terms of the oscillatory Ruderman-Kittel-Kasuya-Yosida interaction between the magnetic moments of the Mn atoms. 30,17,31 The phase separation or miscibility gap in Cu 2 AlMn occurs at temperatures below ϳ600 K ͑see Fig. 1͒, 12 and gives rise to a coexistence region between a nonmagnetic phase and a ferromagnetic phase, with low and high Mn content, respectively.…”