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© 2016 American Physical Society. We demonstrate substantial enhancement in the energy product of MnBi-based magnets by forming robust ferromagnetic exchange coupling between a MnBi layer and a thin CoFe layer in a unique perpendicular coupling configuration, which provides increased resistance to magnetization reversal. The measured nominal energy product of 172kJ/m3 at room temperature is the largest value experimentally attained for permanent magnets free of expensive raw materials. Our finding shows that exchange-coupled MnBi/CoFe magnets are a viable option for pursuing rare-earth-free magnets with energy products approaching those containing rare-earth elements.

Nano-fabrication technologies for realising patterned structures from thin films are reviewed. A classification is made to divide the patterning technologies in two groups namely with and without the use of masks. The more traditional methods as well as a few new methods are discussed al in relation with the application. As mask less methods we discussed direct patterning with ions including FIB, nanopaterning with electron beams, interferometric laser annealing and ion beam induced chemical vapour deposition. The methods using masks are ion irradiation and projection, interference lithography, the use of pre-etched substrates and templates from diblock copolymers and imprint technologies. First a few remarks are given about the magnetic properties of patterned films but the main part of this paper is focussed on the various patterning technologies. Finally two important applications are summarized such as media for ultra high-density recording and magnetic logic devices. Nanometer scale magnetic entities (nanoelements, nanodots, nanomagnets) form a fast growing new area of solid-state physics including the new fields of applications.