Optically Driven Ultrafast Magnetic Order Transitions in Two-Dimensional Ferrimagnetic MXenes

Abstract

Laser-induced switching and manipulation of the spins in magnetic materials are of great interest to revolutionize future magnetic storage technology and spintronics with the fastest speed and least power dissipative. Inspired by the recent discovery of intrinsic two-dimensional (2D) magnets, which provide a unique platform to explore the new phenomenon for light-control magnetism in the 2D limit, we propose to realize light can efficiently tune magnetic states of 2D ferrimagnets in early time. Here, using the 2D ferrimagnetic MXenes (M 2 M'X 2 F 2 , M/M'=Cr, V, Mo; X=C/N) as prototype systems, our realtime density functional theory (TDDFT) simulation show that laser pulses can directly induce ultrafast spin-selective charge transfer between two magnetic sublattices (M and M') on a few femtoseconds, and further generate dramatic changes in the magnetic structure of these MXenes, including a magnetic order transition from ferrimagnetism (FiM) to transient ferromagnetism (FM). The microscopic mechanism underpinning this ultrafast switching of magnetic order in MXenes is governed by optically induced inter-site spin transfer (OISTR) effect, which theoretically enables the ultrafast direct optical manipulation of the magnetic state in MXenes-based 2D materials. Our results open new opportunities for exploring the manipulation of the spin in 2D magnets by optical approaches.

Unravelling Photoinduced Interlayer Spin Transfer Dynamics in Two-Dimensional Nonmagnetic-Ferromagnetic van der Waals Heterostructures

“…The number of unoccupied states is larger in silicene, germanene, and antimonene than in graphene and h -BN in the energy range from 0 to 1.63 eV, where the energy of 1.63 eV represents the frequency of the laser pulse that we used. Such results indicate that the availability of unoccupied states play a key role in the early time spin transfer dynamics and in the demagnetization of 2D vdW NM-FGT heterostructures, as supported by a similar mechanism previously observed in metallic multilayers and MXenes. ,, Moreover, orbitals for Fe, Te, and Si atoms around the Fermi level was dominantly contributed by Fe d xz , Te d xz , and Si p z states. Our orbital diagram also displayed the spin-dependent charge transfer pathway from Fe d xz , to Te d xz , then hops to Si p z states (see Figure S12 in the Supporting Information).…”

Recent Progress on Two-Dimensional Materials

“…These new findings demonstrate the huge potential of novel HER catalysts based on 2D materials [1016][1017][1018][1019][1020] . Currently, the key development in this field is mainly built around the strategies to increase active sites such as the highly active edge sites, grain boundaries 1021 , and sulfur vacancy 1022 .…”

“…The various defect engineering strategies are built on the fact that defects inside or on the surface of the materials can change the coordination environment of the adjacent atoms, and consequently affect the electronic structure and surface properties 1016,[1021][1022][1023][1024][1025] . In an typical example, Li et al study the Sulphur (S) vacancies and strain on the effect of the basal plane of monolayer 2H-phase MoS2 for HER 1022 .…”

“…Both of the ferromagnetism and Tc are significantly enhanced with optical doping e-h pair density increasing, and particularly, Tc is close to room temperature as e-h concentration reaches 3 × 10 13 cm −2 565 . Using real-time time-dependent density functional theory (DFT) simulations, He and coworkers demonstrated that ultrafast spinselective charge transfer between magnetic sublattices can be directly induced by laser pulses in a few femtoseconds in 2D MXenes 1021 . The magnetic structures show dramatic changes under laser excitation.…”

A new family of copper-based MXenes

“…Mixing two transition metals into the same structure through the formation of either solid solutions or ordered double-transition metal MXenes is another way to engineer the MXenes properties. Ordered double-transition MXene sheets present an optically controlled ferrimagnetic to ferromagnetic transition 23 . Mixed functionalized double MXenes show an antiferromagnetic behavior useful to construct 2D-based spin field-effect transistors 26 .…”