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Peter Minch

Publications and source records attributed to Peter Minch.

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First-Principles Study of Magnetism, Electronic Structure, and Bonding in Nb-Mn-Ge Kagome Compounds

In this work, we systematically investigate the magnetic ground states, electronic structures, and bonding characteristics of the computationally predicted stable NbMn6Ge6, NbMn6Ge5, and NbMn6Ge4 using first-principles calculations. Our results show that structurally stable NbMn6Ge6 has a collinear antiferromagnetic configuration, while the metastable rhombohedral NbMn6Ge5 and NbMn6Ge4 favor ferromagnetic ground states. Magnetic moments on Mn atoms are nearly localized, suggesting the applicability of a generalized spin Hamiltonian. Magnetic anisotropy in AFM NbMn6Ge6 and FM NbMn6Ge5 has uniaxial behavior, while FM NbMn6Ge4 has in-plane anisotropy. Charge density difference and electron localization function analyses further show charge redistribution and bonding features within the Mn-Ge Kagome network and between adjacent structural layers. Electronic structures near the Fermi level show no features suitable for topological magnetism studies. Experimental synthesis, structural characterization, and magnetic measurements are required to verify our predictions.

cond-mat.mtrl-sci

Emergent Noncollinearity and Near-Degenerate Magnetic Superlattices in AT6X6 Kagome Metals

Ferromagnetic AT6X6 Kagome compounds are a popular class of systems in which quantum magnetism with topological features has been observed. These systems allow easy chemical substitution, creating an opportunity to fine-tune their properties. In this paper, we present electronic-structure and magnetic ground-state studies of several AT6X6 compounds with relatively low magnetic-ground-state stability. We find unusual magnetic orderings, including complex spin-spiral states and the formation of magnetic long-range superstructures. While LiFe6Ga6 and TiMn6Ge6 retain collinear AFM ground states with low-energy FM/AFM layer sequences, competing spin-spiral and long-period antiferromagnetic structures in MgFe6Ga6 and a double-spin-spiral ground state in TiFe6Ga6 were determined. Magnetism in all these systems appears local, with adiabatic energy profiles suggesting non-Heisenberg long-range interactions, including a strong biquadratic term. In TiMn6Ge6, we found the conditions for magnetic tunneling. Our results show that, in addition to traditional magnetic topological features in such FM Kagome systems, near-degenerate magnetic superstructures suitable for spintronic switching applications can form naturally. Overall, these systems represent a potentially rich playground for neutron diffraction and spintronics experimental studies.

cond-mat.mtrl-sci

Antiferromagnetic Phases in Zr-Fe-Ge Kagome Systems

A wide variety of chemical substitutions in ferromagnetic Kagome systems can lead to diverse magnetic phases with electronic structures suitable for topological or quantum material properties. Here, we study the electronic structure and magnetic orderings using first-principles calculations for the magnetic Kagome compounds ZrFe6Ge6, ZrFe6Ge4, and ZrFe6Ge5. For ZrFe6Ge6, the obtained ground-state magnetic structure is A-type antiferromagnetic (AFM), in agreement with existing experiments. We predicted that the magnetic ground states of ZrFe6Ge4 and ZrFe6Ge5 are collinear A-type bilayer AFM structures with long-period ordering that involves a mix of FM and AFM interlayer orientations. The formation of such long-range magnetic structures appears to be a general feature and is not tied to specific substitutions. The magnetic moments in these systems are largely local and only weakly dependent on the magnetic configuration, with magnitudes in good agreement with available experimental estimates. Neutron scattering experiments, which could provide direct verification of these predictions, are therefore of particular importance.

cond-mat.mtrl-sci

JARVIS-Leaderboard: A Large Scale Benchmark of Materials Design Methods

Lack of rigorous reproducibility and validation are major hurdles for scientific development across many fields. Materials science in particular encompasses a variety of experimental and theoretical approaches that require careful benchmarking. Leaderboard efforts have been developed previously to mitigate these issues. However, a comprehensive comparison and benchmarking on an integrated platform with multiple data modalities with both perfect and defect materials data is still lacking. This work introduces JARVIS-Leaderboard, an open-source and community-driven platform that facilitates benchmarking and enhances reproducibility. The platform allows users to set up benchmarks with custom tasks and enables contributions in the form of dataset, code, and meta-data submissions. We cover the following materials design categories: Artificial Intelligence (AI), Electronic Structure (ES), Force-fields (FF), Quantum Computation (QC) and Experiments (EXP). For AI, we cover several types of input data, including atomic structures, atomistic images, spectra, and text. For ES, we consider multiple ES approaches, software packages, pseudopotentials, materials, and properties, comparing results to experiment. For FF, we compare multiple approaches for material property predictions. For QC, we benchmark Hamiltonian simulations using various quantum algorithms and circuits. Finally, for experiments, we use the inter-laboratory approach to establish benchmarks. There are 1281 contributions to 274 benchmarks using 152 methods with more than 8 million data-points, and the leaderboard is continuously expanding. The JARVIS-Leaderboard is available at the website: https://pages.nist.gov/jarvis_leaderboard

cond-mat.mtrl-sci