We present a high throughput study of the magnetic ground states for 90 transition metal dihalide monolayers TMX using density functional theory based on a collection of Hubbard values. Stable geometrical phases between 2H and 1T are first determined. Spin-polarized calculations show that 50 out of 55 magnetic TMX monolayers are energetically prone to the 1T phase. Further, the magnetic ground states are determined by considering four local spin models with respect to different values. Interestingly, 23 out of 55 TMX monolayers exhibit robust magnetic ground orderings which will not be changed by the values. Among them, NiCl with a magnetic moment of 2 is a ferromagnetic (FM) insulator, while the VX, MnX (X = Cl, Br and I), PtCl and CoI monolayers have noncollinear antiferromagnetic (120°-AFM) ground states with a tiny in-plane magnetic anisotropic energy, indicating flexible magnetic orientation rotation. The exchange parameters for both robust FM and 120°-AFM systems are analyzed in detail with the Heisenberg model. Our high-throughput calculations give a systematic study of the electronic and magnetic properties of TMX monolayers, and these two-dimensional materials with versatile magnetic behavior may have great potential for spintronic applications.
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http://dx.doi.org/10.1039/c9na00588a | DOI Listing |
Phys Chem Chem Phys
January 2025
King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division (PSE), Thuwal 23955-6900, Saudi Arabia.
Employing density functional theory for ground state quantum mechanical calculations and the non-equilibrium Green's function method for transport calculations, we investigate the potential of CdS, ZnS, CdZnS, and ZnCdS as tunnel barriers in magnetic tunnel junctions for spintronics. Based on the finding that the valence band edges of these semiconductors are dominated by p orbitals and the conduction band edges by s orbitals, we show that symmetry filtering of the Bloch states in magnetic tunnel junctions with Fe electrodes results in high tunneling magnetoresistances and high spin-polarized current (up to two orders of magnitude higher than in the case of the Fe/MgO/Fe magnetic tunnel junction).
View Article and Find Full Text PDFInorg Chem
January 2025
Physikalisches Institut, Universität Freiburg, D-79104 Freiburg, Germany.
Understanding the ligand field interactions in lanthanide-containing magnetic molecular complexes is of paramount importance for understanding their magnetic properties, and simple models for rationalizing their effects are much desired. In this work, the equivalence between electrostatic models, which derive their results from calculating the electrostatic interaction energy of the charge density of the 4f electrons in an electrostatic potential representing the ligands, and the common quantum mechanical effective spin Hamiltonian in the space of the ground multiplet is formulated in detail. This enables the construction of an electrostatic potential for any given ligand field Hamiltonian and discusses the effects of the ligand field interactions in terms of an interaction of a generalized 4f charge density with the electrostatic potential.
View Article and Find Full Text PDFJCO Clin Cancer Inform
January 2025
SimBioSys Inc, Chicago, IL.
Purpose: Perfusion modeling presents significant opportunities for imaging biomarker development in breast cancer but has historically been held back by the need for data beyond the clinical standard of care (SoC) and uncertainty in the interpretability of results. We aimed to design a perfusion model applicable to breast cancer SoC dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) series with results stable to low temporal resolution imaging, comparable with published results using full-resolution DCE-MRI, and correlative with orthogonal imaging modalities indicative of biophysical markers.
Methods: Subsampled high-temporal-resolution DCE-MRI series were run through our perfusion model and resulting fits were compared for consistency.
ACS Nano
January 2025
IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, United States.
Lanthanide atoms show long magnetic lifetimes because of their strongly localized 4 electrons, but electrical control of their spins has been difficult because of their closed valence shell configurations. We achieved electron spin resonance of individual lanthanide atoms using a scanning tunneling microscope to probe the atoms bound to a protective insulating film. The atoms on this surface formed a singly charged cation state having an unpaired 6 electron, enabling tunnel current to access their 4 electrons.
View Article and Find Full Text PDFACS Mater Au
January 2025
Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States.
Lanthanide materials with a 4f electron configuration (S) offer an exciting system for realizing multiple addressable spin states for qubit design. While the S ground state of 4f free ions displays an isotropic character, breaking degeneracy of this ground state and excited states can be achieved through local symmetry of the lanthanide and the choice of ligands. This makes Eu attractive as it mirrors Gd in exhibiting the S ground state, capable of seven spin-allowed transitions.
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