Periodic Reporting for period 1 - 2D-SMARTiES (Chemical Design of Smart Molecular/2D Devices for Information Technologies)
Reporting period: 2022-06-01 to 2024-11-30
The final goal of 2D-SMARTiES is to develop a new generation of magnonic devices based on hybrid molecular/2D heterostructures in which a precise control of the spin dynamics can be achieved by external manipulation of stimuli responsive molecules. In particular, we are establishing an efficient general methodology to function as a driving force and guide the synthetic efforts towards the creation of low power consumption and highly tunable nanodevices. This new concept, which goes much beyond the standard chemical functionalization of a 2D magnetic material, may be at the origin of a novel generation of hybrid materials and devices of direct application in emergent areas such as magnonics, spintronics and information technologies.
The project is divided into 3 interrelated work packages (WPs): (WP1) the development of smart organic/2D magnonic heterostructures, (WP2) the creation and study of smart spin crossover/2D magnonics heterostructures and (3) the interplay between smart molecular/2D magnonic heterostructures and topological insulators (WP3). During this period (1 Jun 2022 – 30 Nov 2024), the project has been mainly focused on the development of WP1 and WP2, while some knowledge has been generated for WP3.
The project is divided into 3 interrelated work packages (WPs): (WP1) the development of smart organic/2D magnonic heterostructures, (WP2) the creation and study of smart spin crossover/2D magnonics heterostructures and (3) the interplay between smart molecular/2D magnonic heterostructures and topological insulators (WP3). During this period (1 Jun 2022 – 30 Nov 2024), the project has been mainly focused on the development of WP1 and WP2, while some knowledge has been generated for WP3.
The major research achievement of WP1 has been the development of an efficient and reliable first principles computational framework to model magnetic excitations in 2D magnetic materials and hybrid molecular/2D magnetic heterostructures. We have mainly focused on two families of antiferromagnetic (AF) van der Waals magnets, namely (i) the family of intrinsic AF 2D materials of general formula MPS3, where M = Fe, Co, Ni and Mn, and (ii) the vdW metamagnet CrSBr (AF coupling between layers, FM in the monolayer limit). The main achievements regarding to (i) have been (1) the investigation of the valence band structure of FePS3 using Hubbard-corrected density functional theory and angle-resolved photoemission spectroscopy (ARPES). This has allowed to benchmark our ab initio calculations and provide an important step towards an accurate theoretical description of the electronic properties of transition metal phosphorus trisulfides; (2) unraveling the microscopic origin of the magnetization-induced anisotropic strain in CoPS3 and FePS3 using DFT and a derived orbital-resolved magnetic exchange analysis. The paper, in collaboration with experimental groups, measures the temperature dependence of the chemical structures via the evolution of the anisotropy in the resonance frequency of rectangular membranes; (3) the investigation of the crystal, electronic and magnetic structures of selenized Janus monolayers based on NiPS3 and MnPS3 from first principles. We also calculated the magnon dispersion and performed real-time real-space atomistic dynamic simulations to explore the propagation of spin waves in these 2D AF materials, analysing the effects of the induced broken inversion symmetry in the 2D Janus layers and highlighting their potential for magnonics; and (4) the simulation of a vdW heterostructure formed by FePS3 on MoS2, in collaboration with experimental groups, demonstrating the control of optical properties in MoS2 through charge transfer processes. We identified the key role of the presence of vacancies in the material. On the other hand, regarding CrSBr, we have reported the (5) development of an unprecedented chemical approach to magnonics based on hybrid molecular/CrSBr heterostructures; (6) the development of a magnonic gas sensing device based on CrSBr; (7) proximity effects in a 2D superconductor in a CrSBr/NbSe2; (8) magnetic anisotropy and dipolar interactions in CrSBr. Furthermore, we have also unveiled the origin of the high-temperature magnetism in Fe3GaTe2, a 2D ferromagnet using the methodology developed in the project.
The major research achievements of WP2 can be divided into two categories, (i) the modelling of uniform strain effects in 2D materials of interest for magnonics and (ii) the screening of magnetic molecules that can be potential candidates to create new hybrid heterostructures with 2D materials. Regarding (i), we have provided (1) the first investigation of strain engineering of magnetic excitations in a 2D magnetic material, showing that the magnon dynamics can be modified selectively along the two main crystallographic directions as a function of applied strain and critical temperatures can be enhanced up to 30%, allowing the propagation of spin waves at higher temperatures; (2) the study of topological magnons in single-layer transition metal trihalides using a fully self-consistent Hubbard-corrected DFT methodology and their control through strain-engineering. On the other hand, in the second category, (3) we have published a meta-study that incorporates all molecular magnets discovered up to 2019, offering a highly useful application (SIMDAVIS). We used statistical analysis, and included results from more than 1400 compounds; and (4) a full analysis of spin-phonon coupling in magnetic 2D metal-organic frameworks, providing chemical insights to improve the performance of these magnetic 2D MOFs based on the effective manipulation of the phonon modes that can present a major impact on their magnetic properties.
The major research achievements of WP3 are based on materials with strong spin-orbit coupling: (1) the theoretical investigation of hexagonal hybrid bismuthene by interface engineering using first principles, we revealed this new hybrid covalent heterostructure; (2) modelling of the covalent functionalization of antimonene by graphene; and (3) the determination of the band structure in the AuSn4 superconductor. All these three works have been in collaboration with experimental groups. These results have provided excellent feedback for our theoretical and computational approaches.
The major research achievements of WP2 can be divided into two categories, (i) the modelling of uniform strain effects in 2D materials of interest for magnonics and (ii) the screening of magnetic molecules that can be potential candidates to create new hybrid heterostructures with 2D materials. Regarding (i), we have provided (1) the first investigation of strain engineering of magnetic excitations in a 2D magnetic material, showing that the magnon dynamics can be modified selectively along the two main crystallographic directions as a function of applied strain and critical temperatures can be enhanced up to 30%, allowing the propagation of spin waves at higher temperatures; (2) the study of topological magnons in single-layer transition metal trihalides using a fully self-consistent Hubbard-corrected DFT methodology and their control through strain-engineering. On the other hand, in the second category, (3) we have published a meta-study that incorporates all molecular magnets discovered up to 2019, offering a highly useful application (SIMDAVIS). We used statistical analysis, and included results from more than 1400 compounds; and (4) a full analysis of spin-phonon coupling in magnetic 2D metal-organic frameworks, providing chemical insights to improve the performance of these magnetic 2D MOFs based on the effective manipulation of the phonon modes that can present a major impact on their magnetic properties.
The major research achievements of WP3 are based on materials with strong spin-orbit coupling: (1) the theoretical investigation of hexagonal hybrid bismuthene by interface engineering using first principles, we revealed this new hybrid covalent heterostructure; (2) modelling of the covalent functionalization of antimonene by graphene; and (3) the determination of the band structure in the AuSn4 superconductor. All these three works have been in collaboration with experimental groups. These results have provided excellent feedback for our theoretical and computational approaches.
The main groundbreaking advances beyond state-of-the-art that push the boundaries of 2D magnetism and their applications in magnonics are (1) the study on magnon straintronics in CrSBr, which unveils an unprecedented capability to modulate magnon dynamics by selectively altering spin wave propagation along specific crystallographic directions, and (2) the introduction of molecular-controlled magnonics, based on hybrid molecular/2D heterostructures. These results establish a transformative approach for tuning magnetic and magnonic properties chemically, which is unprecedented. Interestingly, after our publication, the first experimental evidence of magnons tuned by molecules have been published (ACS Appl. Electron. Mater. 2024, 6, 6, 4232–4238), in which the authors use the magnetic insulator Y3Fe5O12 (YIG) and a cobalt phthalocyanine molecular layer, obtaining larger amplitudes of nonlocal signals for both electrically and thermally excited magnon currents in the hybrid material. Thus, our approach has been pioneer paving the way to the use of molecular functionalization to modulate and enhance transport in magnetic insulators through interfacial hybridization. Other advances worth to mention are the simulation of the magnon topological gap using a fully first-principles methodology –zero-free parameter– in CrI3, the benchmarking of the DFT+U simulations using ARPES measurements and the explanation of the microscopic origin of the spontaneous magnetostriction in FePS3 and CoPS3, among other discoveries.