Optimization of energy product and reversal process for Nd_2Fe_(14)B/α'-(FeCo)_(16)N_2/Nd_2Fe_(14)B exchange-spring trilayer films

摘要

Highlights • Nd2Fe14B/α″-(FeCo)16N2 may be one of the most promising exchange spring systems to achieve maximum energy product. • The trilayers system presents larger energy products than bilayers system. • The symmetrical sandwich structure can realize the largest energy product. Abstract The influence of the structure on the energy product for the exchange-coupled Nd2Fe14B/α″-(FeCo)16N2 films has been investigated, and the magnetic properties of the trilayer system have been analyzed based on the micromagnetic simulation software object-oriented micromagnetic framework. The numerical results show that the energy product and the magnetic properties change with the bilayers to trilayers, where the maximum energy products of the bilayer and trilayer systems are 589 and 833.52kJ/m3, respectively. The dependence of the magnetic properties on the structure of the trilayer system was also considered. The symmetrical sandwich structure was observed to achieve a large energy product. In addition, hysteresis loops, energy product, and magnetic reversal process for the exchange-spring trilayer system were investigated. The optimal thickness of the soft phase is 7nm with the largest maximum energy product. (BH)max was observed to decrease with the increase of β, where β is the angle between the applied field and the easy axis. The trilayer system achieves the largest maximum energy product when β =0°.