Magnetism in EuAlSi and the Eu_1−𝑥⁢Sr_𝑥⁢ AlSi solid solution solid solution

Journal Article · Wed Aug 06 00:00:00 EDT 2025 · Physical Review Research

DOI:https://doi.org/10.1103/69sn-hpxm· OSTI ID:2584464

Walicka, Dorota I. ^[1]; Blacque, Olivier ^[2]; Gornicka, Karolina ^[3]; White, Jonathan S. ^[4]; Klimczuk, Tomasz ^[5]; von Rohr, Fabian O. ^[6]

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1. University of Geneva (Switzerland); University of Zurich (Switzerland); Paul Scherrer Inst. (PSI), Villigen (Switzerland)
2. University of Zurich (Switzerland)
3. Gdansk University of Technology (Poland); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
4. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
5. Gdansk University of Technology (Poland)
6. University of Geneva (Switzerland)

The magnetic properties of EuAlSi, a compound comprising a honeycomb lattice of Al/Si atoms and a triangular lattice of Eu atoms, are presented. By means of single-crystal x-ray diffraction, we find that EuAlSi crystallizes in an AlB₂-type structure with space group 𝑃⁢6/mmm and unit cell parameters 𝑎 = 4.2229⁢ (10) ⁢Å and 𝑐 = 4.5268 ⁢(12)⁢ Å. Our magnetic measurements indicate that EuAlSi is a soft ferromagnetic material with 𝑇_Curie = 25.8 K. The susceptibility follows the Curie-Weiss law at high temperatures, which allowed us to determine the paramagnetic Curie temperature 𝜃_𝑃 = 36.2 ⁢(1) ⁢K and an effective magnetic moment 𝜇_eff = 8.07 ⁢(1)⁢ µ_𝐵/Eu. This value is in agreement with the theoretical value of 7.9 µ_𝐵 for Eu²⁺ free ion. Moreover, we have prepared the Eu_1−𝑥⁢Sr_𝑥⁢ AlSi solid solution, where the atoms in the triangular lattice were systematically exchanged, in order to study the evolution of the collective quantum properties from the ferromagnetic EuAlSi toward the superconducting SrAlSi. Across the Eu_1−𝑥⁢Sr_𝑥 AlSi solid solution, the unit cell parameters change linearly, following Vegard’s law, and making the system reliable for studying composition dependence of the interplay between the crystal structure and physical properties. As the Sr content increases, i.e., 𝑥 increases, we note a consistent reduction of 𝜇_eff and 𝑇_Curie. Long-range magnetic order in Eu_1−𝑥⁢Sr_𝑥⁢ AlSi persists up to 𝑥 = 0.95, whereas superconductivity is only observed for samples with 𝑥 > 0.97.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: Swiss National Science Foundation (SNSF); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 2584464
• Journal Information: Physical Review Research, Journal Name: Physical Review Research Journal Issue: 3 Vol. 7; ISSN 2643-1564
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English