Effect of magnetism and temperature on the stability of (Crx,V1x)2AlC phases

Joás Grossi, Shafqat H. Shah, Emilio Artacho, and Paul D. Bristowe
Phys. Rev. Materials 2, 123603 – Published 26 December 2018

Abstract

The stability of (Crx,V1x)2AlC MAX phases, materials of interest for a variety of magnetic as well as high-temperature applications, has been studied using density-functional-theory first-principles calculations. The enthalpy of mixing predicts these alloys to be unstable towards unmixing at 0 K. The calculations also predict, however, that these phases would be thermally stabilized by configurational entropy at temperatures well below the values used for synthesis. The temperature Ts below which they become unstable is found to be quite sensitive to the presence of magnetic moments on Cr ions, as well as to the material's magnetic order, in addition to chemical order and composition. Allowing for magnetism, the value of Ts for (Cr0.5,V0.5)2AlC with chemically disordered Cr and V atoms is estimated to be between 516 and 645 K depending on the level of theory, while if constrained to spin paired, Ts drops to 142 K. Antiferromagnetic spin arrangements are found to be favored. The combination of antiferromagnetic frustration and configurational disorder should give rise to interesting spin textures at low temperatures.

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  • Received 16 July 2018
  • Revised 28 October 2018

DOI:https://doi.org/10.1103/PhysRevMaterials.2.123603

©2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Joás Grossi1,2, Shafqat H. Shah3, Emilio Artacho2,4,5, and Paul D. Bristowe3

  • 1Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, 5500 Argentina
  • 2Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, J. J. Thomson Ave, Cambridge CB3 0HE, United Kingdom
  • 3Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Rd, Cambridge CB3 0FS, United Kingdom
  • 4CIC Nanogune and DIPC, Tolosa Hiribidea 76, 20018 San Sebastián, Spain
  • 5Basque Foundation for Science Ikerbasque, 48013 Bilbao, Spain

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Issue

Vol. 2, Iss. 12 — December 2018

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