R&D: Simulation of Chemical Order-Disorder Transitions Induced Thermally at Nanoscale for Magnetic Recording and Storage

ACS Applied Nano Materials has published an article written by Nikolay I. Polushkin, Institute for Physics of Microstructures, Russian Academy of Sciences, 603807 Nizhny Novgorod, Russian Federation, Thomas B. Möller, Department of Physics, University of Konstanz, 78457 Konstanz, Germany, Sergey Bunyaev, Artem Bondarenko, Institute of Physics for Advanced Materials, Nanotechnology and Photonics (IFIMUP)/Departamento de Física e Astronomia, Universidade do Porto, 4169 – 007 Porto, Portugal, Miao He, Maxim V. Shugaev, Department of Materials Science and Engineering, University of Virginia , 395 McCormik Road, Charlottesvil le, Virginia 22904-4745, USA, Johannes Boneberg, Department of Physics, University of Konstanz, 78457 Konstanz, Germany, and Gleb N. Kakazei, Institute of Physics for Advanced Materials, Nanotechnology and Photonics (IFIMUP)/Departamento de Física e Astronomia, Universidade do Porto, 4169 – 007 Porto, Portugal.

Abstract: “In memory nanodevices based on phase changes induced thermally, the process of information recording is a reversible transition between the structurally ordered (crystalline) and disordered (amorphous) phases that can provide a difference in the physical properties of these two states, e.g., in optical reflectivity, electrical resistivity, or magnetic permeability. It is of special interest to explore whether the chemical disorder is erasable, rewritable, and scalable in solid alloys upon their exposure to short heating pulses. Here, we model this process by assuming second-order phase transitions between chemically ordered and disordered states in the atomic lattice. Our simulations reveal that nanosecond laser irradiation concentrated within a nanoscale spot on the sample surface is able to induce reversible chemical-order (B2)-disorder (A2) transformations (CODTs) in intermetallic Fe-rich Fe_xAl_1-x alloys that exhibit the disorder-induced ferromagnetism. A realization of this concept would provide an alternative approach to current technologies for magnetic recording and data storage, in which the written bits are represented by regions with not a different polarity but with a different magnitude of magnetization. We envision that the proposed approach can be realized with tools used currently for heat-assisted magnetic recording (HAMR), e.g., with a near-field transducer (NFT). A specific design for CODT-based magnetic recording media is proposed.“