Seznam abstraktů 2021: PLENÁRNÍ SEKCE

Discovery of new materials provides moments of inspiration and shifts in understanding, shaping the dynamic field of materials science. Following the graphene breakthrough, many other 2D materials emerged. Although many of them remain subjects of purely academic interest, others have jumped into the limelight due to their attractive properties, which have led to practical applications. Among the latter are 2D carbides and nitrides of transition metals known as MXenes [1]. The family of MXenes has been expanding rapidly since the discovery of Ti3C2 in 2011. More than 30 different stoichiometric MXenes have been reported, and the structure and properties of numerous other MXenes have been predicted. Moreover, the availability of solid solutions on M and X sites, multi-element high-entropy MXenes, control of surface terminations, and the discovery of out-of-plane ordered double-M o-MXenes (e.g., Mo2TiC2), as well as in-plane ordered i-MAX phases and their i-MXenes offer a potential for producing dozens of new distinct structures. This presentation will describe the state of the art in the manufacturing of MXenes, their delamination into single-layer 2D flakes and assembly into films, fibers and 3D structures. Synthesis-structure-properties relations of MXenes will be addressed on the example of Ti3C2. The versatile chemistry of the MXene family renders their properties tunable for a large variety of applications. In particular, the interaction of MXenes with electromagnetic waves can be controlled via their composition and structure. Many MXenes offer high electronic conductivity and outstanding electromagnetic interference shielding. They can also be used in telecommunication, energy, medical and electronic device applications.
REFERENCE: [1] A. VahidMohammadi, J. Rosen, Y. Gogotsi, The World of Two-Dimensional Carbides and Nitrides (MXenes), Science, 372, eabf1581 (2021).

Solid state memory technology is fundamentally divided into volatile memories (e.g. DRAMs, allowing for fast data access, unable to store data for periods of time longer than a few ms), and non-volatile memories (e.g. Flash, for which the opposite holds true). Hybridisation of both, bringing together the advantages of both types, i.e. long storage times, short write, read and erase times, has been referred to as the “Holy Grail”. This Holy Grail offers unique functionalities, and ensures future progress of memory development after the end of Moore’s law. The feasibility of our QD-Flash concept, its fast write and erase times, will be demonstrated. The goal of non-volatility has almost been reached, 4 days at room temperature being the best result reported worldwide. The storage time of holes in (InGa)Sb QDs embedded in a (AlGa)P matrix can be extended to 10 y at room temperature. Tunneling structures will solve the trade-off conflict between storage and erase times. The combination of low-voltage operation and small capacitance suggests a switching energy per unit area 100 to 1000 times smaller than DRAM and Flash, respectively. The road map to realize the final steps for the „Holy Grail“ will be laid-out.

Fifty years ago, Louis Néel pointed out in his Nobel lecture that while interesting from theoretical viewpoint, antiferromagnets did not seem to have any applications. Indeed, the alternating directions of magnetic moments on neighboring atoms and the resulting zero net magnetization have made antiferromagnets hard to control by the magneto-recording tools common in ferromagnets. This has hindered both the research and utility of these abundant magnetic materials. Our experimental demonstrations of reading and writing information in antiferromagnets have prompted the current rapidly growing interest in this traditionally overlook class of magnets. Besides electronic memory devices, antiferromagnetic spintronics has also demonstrated its utility in the research of ultra-fast optical manipulation of magnets, or analog neuromorphic logic-in-memory computing. Most recently, the research of antiferromagnetic spintronic phenomena inspired us to revisit the fundamentals of magnetism. As a result, we have delimited from antiferromagnets a third distinct class of magnetic order, the so-called altermagnetism, in which the spin direction alternates in both the crystal-structure and band-structure of the magnet. This can have consequences in fields ranging from spintronics to topological dissipationless nano-electronics.