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Fast ab initio design of high-entropy magnetic materials

https://doi.org/10.1103/PhysRevMaterials.9.L031401

Bista, Dinesh; Beeson, Willie_B; Sengupta, Turbasu; Jackson, Jerome; Khanna, Shiv_N; Liu, Kai; Yin, Gen (March 2025, Physical Review Materials)
Single‐Phase L 1 ₀ ‐Ordered High Entropy Thin Films with High Magnetic Anisotropy

https://doi.org/10.1002/advs.202308574

Beeson, Willie_B; Bista, Dinesh; Zhang, Huairuo; Krylyuk, Sergiy; Davydov, Albert_V; Yin, Gen; Liu, Kai (June 2024, Advanced Science)

Abstract The vast high entropy alloy (HEA) composition space is promising for discovery of new material phases with unique properties. This study explores the potential to achieve rare‐earth‐free high magnetic anisotropy materials in single‐phase HEA thin films. Thin films of FeCoNiMnCu sputtered on thermally oxidized Si/SiO₂substrates at room temperature are magnetically soft, with a coercivity on the order of 10 Oe. After post‐deposition rapid thermal annealing (RTA), the films exhibit a single face‐centered‐cubic phase, with an almost 40‐fold increase in coercivity. Inclusion of 50 at.% Pt in the film leads to ordering of a singleL1₀high entropy intermetallic phase after RTA, along with high magnetic anisotropy and 3 orders of magnitude coercivity increase. These results demonstrate a promising HEA approach to achieve high magnetic anisotropy materials using RTA.
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CoTe ₂ : A Quantum Critical Dirac Metal with Strong Spin Fluctuations

https://doi.org/10.1002/adma.202300640

Siegfried, Peter_E; Bhandari, Hari; Qi, Jeanie; Ghimire, Rojila; Joshi, Jayadeep; Messegee, Zachary_T; Beeson, Willie_B; Liu, Kai; Ghimire, Madhav_Prasad; Dang, Yanliu; et al (April 2023, Advanced Materials)

Abstract Quantum critical points separating weak ferromagnetic and paramagnetic phases trigger many novel phenomena. Dynamical spin fluctuations not only suppress the long‐range order, but can also lead to unusual transport and even superconductivity. Combining quantum criticality with topological electronic properties presents a rare and unique opportunity. Here, by means of ab initio calculations and magnetic, thermal, and transport measurements, it is shown that the orthorhombic CoTe₂is close to ferromagnetism, which appears suppressed by spin fluctuations. Calculations and transport measurements reveal nodal Dirac lines, making it a rare combination of proximity to quantum criticality and Dirac topology.
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