High-intensity laser irradiation can effectively couple to practically all kinds of materials, causing modification of their physical properties due to laser-induced phase transformations. This gives rise to a broad field of laser micro- and nanofabrication with its various technological applications. We demonstrate that, in a 40-nm-thick film of ${\mathrm{Fe}}_{60}{\mathrm{Al}}_{40}$ alloy, a short laser pulse is capable of (re)writing the ferromagnetism observed at room temperature (RT). The energy of the pulse generating a ferromagnetic region has to be sufficiently high to induce melting of the ${\mathrm{Fe}}_{60}{\mathrm{Al}}_{40}$ layer, while the ferromagnetic state can be erased by various kinds of lower-intensity thermal treatment. This cycling of RT ferromagnetism can be explained in terms of the chemical order (B2)-disorder (A2) phase transition in the ${\mathrm{Fe}}_{60}{\mathrm{Al}}_{40}$ crystal lattice, which is affected by laser-induced melting and rapid resolidification. Our finding has implications for the development of a magnetic memory technology that would use the reversibility of the modulus of the magnetization vector instead of its direction. This promises to circumvent the problem of the superparamagnetic limit for magnetic data storage density.

• Received 16 October 2017
• Revised 30 May 2017

DOI:https://doi.org/10.1103/PhysRevApplied.10.024023