Funding application supported

The project of our team "Investigation of new approaches for synthesizing nanodiamonds with pressureless mechanisms" was supported by the Russian Science Foundation!»

Nanometer-sized diamond particles, or nanodiamonds, have attracted the attention of various researchers due to their unique properties, which are promising in the various fields of industry, quantum computing, biological and environmental applications. Unlike other carbon nanostructures, nanodiamonds can be scaled from nearly 0D to 3D particles with varying surface functionalization, which allows their physicochemical characteristics to be controlled over a wide range. The availability of efficient methods for the synthesis of nanodiamonds is a critical challenge for their widespread application. Currently, nanodiamonds are mainly obtained by detonation or grinding of macroscopic diamond. These standard methods share the common disadvantages of poor control of nanodiamond size, shape and degree of contamination. However, there are other methods to produce a diamond phase from sp²-hybridized carbon, such as by irradiating graphene with ions or by a chemically induced phase transition. Nevertheless, the mechanisms underlying these approaches are still insufficiently studied. For example, the appearance of nanodiamonds in multilayer graphene after irradiation with high-energy ions at first glance contradicts thermodynamic estimates. Therefore, a detailed study of the conditions and mechanisms of such photoinduced phase transformation using modern methods of computer modeling is a new and urgent task. Other important objectives of the project are to study the formation of nanometer-sized diamond clusters as a result of chemically induced phase transition, as well as the controlled growth of nanodiamonds using 2D diamond as a substrate. This process may allow the formation of a defect-free diamond structure with a predetermined surface. On the other hand, the planned research in the project is also aimed at studying the possibility of controlled introduction of defects into diamond necessary for the realization of single-photon emission and the application of such nanostructures in quantum computers and other fields.

The project PI is Dr. Sergey Erohin.

Funding application supported

The project of our team "Modelling of low-dimensional magnetic heterostructures for next-generation spintronic devices" was supported by the Russian Science Foundation!»

The challenge of finding new ways of storing and processing information is extremely relevant nowadays, as traditional silicon technologies have actually reached the limit of information recording density and further miniaturization. One solution to this problem is to consider the electron as a charge carrier with two main "degrees of freedom" determined by its spin. Thus, due to giant and tunnel magnetoresistance effects, spin transfer effects and a number of other fundamental properties, spintronic devices, the basis of a new generation of information storage and processing technology, are now being actively developed. However, despite the proven high potential of spintronic technology (in terms of low power consumption and speed), it is still in its infancy in the consumer market. magnetoresistive random-access memory (MRAM) is expected to be able to compete with conventional flash memories. But to achieve this, a number of challenges must be met, requiring advances in the synthesis of stable nanoscale heterostructures and ways to control their properties at the atomic level. Two-dimensional materials can play a key role in solving these problems. Indeed, since the discovery of graphene and related materials, atomic-thick films have been viewed as a potential component of ultra-compact device architecture and radically new ways to process information. Scientific advances in spintronic devices based on 2D materials, as well as recent progress in large-scale co-integration of 2D structures with traditional microelectronic materials, have opened promising prospects for MRAM technology development. The project proposes the first comprehensive theoretical investigation of a range of promising magnetic tunneling junctions (MTJ) based on ferromagnetic and 2D materials, for which magnetoresistance and spin injection effects - the basis of spin valves and transistors - can be observed. For example, new interfaces based on iron and cobalt, including half-metallic Heusler alloys, and their heterojunction with two-dimensional structures such as graphene and transition metal dichalcogenides with different compositions will be investigated. Despite the wide popularity of these materials separately, heterostructures based on them are poorly understood, and experimental work and further applications for spintronic applications require a detailed theoretical analysis of the structure, properties and nature of the spintronic effects. In this project, quantum-chemical simulations and nonequilibrium transport methods will be used for the first time to obtain detailed information on the electronic and magnetic configuration of the most promising MTJs, to describe the equilibrium properties of heterojunctions, and to calculate the quantum conductivity and to study the tunneling magnetoresistance effect. Moreover, tunnel heterostructures with an embedded MoO3 oxide layer, a promising for efficient spin injection in two-dimensional materials due to the proximity effect, will be modelled and studied for the first time. The results will significantly extend the field of knowledge about the spin-transport properties of new magnetic heterostructures based on experimentally known ferromagnetic materials and two-dimensional films. The prospects for their application in magnetoresistive and other spintronic devices will also be substantiated in detail.

The project PI is Dr. Konstantin Larionov

Funding application supported

The project of our team "Investigation of phase transitions in carbon materials at the atomic level using modern modelling techniques" was supported by the Russian Science Foundation!»

A variety of first order phase transitions in their development pass through the same stages, the first of which is the nucleation, the most interesting and the most complicative for investigation. In the theory of this stage the questions of thermodynamics of small systems and the description of the process of overcoming the energy barrier by nucleating particles are closely intertwined. Computer simulation techniques are required to achieve a detailed understanding of nucleation. The small size of the new phase nucleus require taking into account the contributions of interface energy, surface energy, the relaxation of mechanical stresses in the energy of curvature and other features of low-dimensional materials. This demands high-precision simulation that takes all these parameters into account, which, however, is an extremely challenging task for the current toolset of computational material science. Indeed, traditional methods of the density functional theory, although they allow one to accurately enough calculate the properties of atomic systems from first principles, are nevertheless limited by the computing power available. This limits their applicability to periodic structures consisting of hundreds of atoms. At the same time the problem of describing nucleation of new phases requires the description of systems with a number of atoms up to 10^4-10^6. On the other hand, empirical potentials, which are not demanding for computational resources, allow to describe large systems containing millions of atoms. But until recently, parametrization of these potentials has been limited to their (often rather narrow) model systems, not intended for the simulation of transition states and new phases, which is a necessary condition for the study of phase transformations. However, the situation has changed dramatically recently with the developing of empirical machine learning potentials that can be trained on a large data set derived from ab initio calculations. Thus, one of the challenges of the project is to develop such potentials describing interactions with the accuracy of first principles methods to model the required number of atoms in the structures. Parametrized potentials will be applied to describe phase transformations in carbon systems, graphite-diamond transition and multilayer graphene-diamond ultrathin film (diamane) and may be further used to describe phase transitions in other systems as well.

The project PI is Dr. Sergey Erohin.