Complex magnetism of single-crystalline AlCoCrFeNi nanostructured high-entropy alloy
Primož Koželj,
Andreja Jelen,
Goran Dražić,
Stanislav Vrtnik,
Jože Luzar,
Magdalena Wencka,
Anton Meden,
Michael Feuerbacher,
Janez Dolinšek
Affiliations
Primož Koželj
Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; University of Ljubljana, Faculty of Mathematics and Physics, Jadranska 19, SI-1000 Ljubljana, Slovenia
Andreja Jelen
Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
Goran Dražić
National Institute of Chemistry, Department of Materials Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
Stanislav Vrtnik
Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
Jože Luzar
Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
Magdalena Wencka
Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, PL-60-179 Poznań, Poland
Anton Meden
University of Ljubljana, Faculty of Chemistry and Chemical Technology, Večna Pot 113, SI-1000 Ljubljana, Slovenia
Michael Feuerbacher
Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; Corresponding author
Janez Dolinšek
Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; University of Ljubljana, Faculty of Mathematics and Physics, Jadranska 19, SI-1000 Ljubljana, Slovenia; Corresponding author
Summary: We have investigated magnetism of the Al28Co20Cr11Fe15Ni26 single-crystalline high-entropy alloy. The material is nanostructured, composed of a B2 matrix with dispersed spherical-like A2 nanoparticles of average diameter 64 nm. The magnetism was studied from 2 to 400 K via direct-current magnetization, hysteresis curves, alternating-current magnetic susceptibility, and thermoremanent magnetization time decay, to determine the magnetic state that develops in this highly structurally and chemically inhomogeneous material. The results reveal that the Cr-free B2 matrix of composition Al28Co25Fe15Ni32 forms a disordered ferromagnetic (FM) state that undergoes an FM transition at TC≈ 390 K. The Al- and Ni-free A2 nanoparticles of average composition Co19Cr56Fe25 adopt a core-shell structure, where the shells of about 2 nm thickness are CoFe enriched. While the shells are FM, the nanoparticle cores are asperomagnetic, classifying into the broad class of spin glasses. Asperomagnetism develops below 15 K and exhibits broken-ergodicity phenomena, typical of magnetically frustrated systems.
