Unveiling a New Class of Quasi-One-Dimensional van der Waals Crystal with Tunable Electronic and Magnetic Properties
Abstract
The success in exfoliating quasi-one-dimensional van der Waals (vdW) magnets to produce one-dimensional nanostructures with a stable long-range magnetic ordering at finite temperatures has ignited significant interest in exploring vdW crystals with unique electronic and magnetic properties. Here in, using a predictive density functional theory, we investigated a new class of vdW magnet, Cr1-xMnxSbSe3 (x = 0, 0.5, 1), and revealed the mechanisms underlying their distinct magnetic behaviors. Our findings show that CrSbSe3 is a ferromagnetic semiconductor with a Curie temperature of ∼70 K, in agreement with experimental observations. The indirect exchange mechanism mediated by selenium atoms is identified as the driver of its ferromagnetic ordering. For Cr0.5Mn0.5SbSe3, we observe half-metallic ferromagnetism with a Curie temperature of ∼40 K, while MnSbSe3 exhibits an antiferromagnetic metallic behavior. The magnetic ordering in these systems is attributed to Ruderman-Kittel-Kasuya-Yosida interaction mediated by itinerant electrons from selenium. In addition, CrSbSe3 features a Dirac cone-like band dispersion at the high-symmetry R-point for the spin majority channel, ∼0.80 eV below the Fermi energy, with a maximum quasiparticle velocity of 1.49 × 105 m/s, which is comparable to the Fermi velocity in graphene. Upon 50% substitution of Cr by Mn, the Dirac-cone shifts closer to the Fermi energy, with the quasiparticle velocity increasing to 4.2 × 105 m/s. Further, the observation of nonlinear dispersion away from the R-point indicates that the quasiparticles transition from a massless behavior in one region of the Brillouin zone to a massive behavior in other regions. These tunable electronic behaviors and exchange mechanisms underscore the potential of compositional modifications for engineering novel low-dimensional magnets, paving the way for their future applications in next-generation spintronics.