Magnetic properties of the CrMnFeCoNi high-entropy alloy

Abstract

We present experimental data showing that the equiatomic CrMnFeCoNi high-entropy alloy undergoes two magnetic transformations at temperatures below 100 K while maintaining its FCC structure down to 3 K. The first transition, paramagnetic to spin glass, was detected at 93 K and the second transition of the ferromagnetic type occurred at 38 K. Field-assisted cooling below 38 K resulted in a systematic vertical shift of the hysteresis curves. Strength and direction of the associated magnetization bias was proportional to the strength and direction of the cooling field and shows a linear dependence with a slope of 0.006 ± 0.001 emu/T. The local magnetic moments of individual atoms in the CrMnFeCoNi quinary FCC random solid solution were investigated by ab initio (electronic density functional theory) calculations. Results of the numerical analysis suggest that, irrespective of the initial configuration of local magnetic moments, the magnetic moments associated with Cr atoms align anti-ferromagnetically with respect to a cumulative magnetic moment of their first coordination shell. The ab initio calculations further showed that the magnetic moments of Fe and Mn atoms remain strong (between 1.5 and 2 µB) while the local moments of Ni atoms effectively vanish. These results indicate that interactions of Mn-and/or Fe-located moments with the surrounding magnetic structure account for the observed macroscopic magnetization bias.

Modeling the structure and thermodynamics of high-entropy alloys

“…In this limit, an effective spin S can be defined for each atom, and the entropy approximated as k B ln(2S 1 1). Although rigorous calculation of magnetic entropy is not yet available for HEAs, experimental information is available [76][77][78] owing to the possible application of HEAs in magnetic refridgeration. 21…”

Unveiling the mechanism of abnormal magnetic behavior of FeNiCoMnCu high-entropy alloys through a joint experimental-theoretical study

“…The mechanical properties of HEAs have been extensively studied [12][13][14][15][16][17] but their functional properties are less explored. Most recent studies on functional properties of HEAs have addressed thermal, electrical, and magnetic properties, yet detailed studies on the underlying mechanisms are still rare [18][19][20][21][22][23][24][25][26]. While as an example for specific functional properties the resistive and superconducting properties of a TaNbHfZrTi HEA with a critical temperature of 7.3 K have been addressed [20], long term benefits could arise from HEAs with combinations of good mechanical and functional properties.…”

A Review of Multi-Scale Computational Modeling Tools for Predicting Structures and Properties of Multi-Principal Element Alloys

“…Such studies and models are scarce in the literature, and also for verification and validation of such models high-throughput and in-situ experiments are required. [129,130]; i: [131,132]; j: [133][134][135][136][137][138][139][140][141].…”

“…It was found that the vacancy significantly affects its surrounding local spin magnetic moment. In another study, DFT calculations and five different experimental methods were combined and utilized to determine the magnetic ordering in the CoCrFeMnNi MPE alloys [135]. Their first-principles calculations showed that interactions of Fe-located and/or Mn-located moments with the nearby magnetic structure may be responsible for the experimental macroscopic magnetization bias.…”