skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


This content will become publicly available on April 27, 2026

Title: Switching of Magnetic Order via Non‐Magnetic Al Addition in FeCoNiMnAl x Films
Abstract Magnetic high entropy alloys (HEAs) consisting of 3dtransition metals offer an exciting platform to explore novel magnetic phases as they often house competing exchange interactions in combination with random site disorders. In this work, a sensitive and tunable magnetic order is demonstrated in sputtered single‐layer FeCoNiMnAlxfilms, as a function of non‐magnetic Al addition, along with an unexpected exchange bias effect. Thin films of 50 nm FeCoNiMn exhibit a face‐centered‐cubic (fcc) phase, reentrant spin glass (SG) transition near 100 K, and a large exchange bias of over 500 Oe after field‐cooling to 5 K. The exchange bias is increased to 930 Oe through a small addition of 5 at.% Al. Further Al addition to 12 at.% results in a body‐centered‐cubic (bcc) phase, coinciding with a large increase in the saturation magnetization, decrease of exchange bias to 50 Oe, and suppression of SG behavior. The change in magnetic order across the Al‐induced structural transformation is mediated by the switching of Mn ground state from AF to FM, which is supported by first‐principles calculations and experimentally confirmed via X‐ray magnetic circular dichroism. These results open up new HEA strategies for explorations of novel magnetic phases.  more » « less
Award ID(s):
2151809 2429995 1828420
PAR ID:
10585645
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
Wiley
Date Published:
Journal Name:
Advanced Functional Materials
ISSN:
1616-301X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; (, 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. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Proceedings of the National Academy of Sciences)
    We present a comprehensive study of the inhomogeneous mixed-valence compound, EuPd3S4, by electrical transport, X-ray diffraction, time-domain151Eu synchrotron Mössbauer spectroscopy, and X-ray absorption spectroscopy measurements under high pressure. Electrical transport measurements show that the antiferromagnetic ordering temperature,TN, increases rapidly from 2.8 K at ambient pressure to 23.5 K at ~19 GPa and plateaus between ~19 and ~29 GPa after which no anomaly associated withTNis detected. A pressure-induced first-order structural transition from cubic to tetragonal is observed, with a rather broad coexistence region (~20 GPa to ~30 GPa) that corresponds to theTNplateau. Mössbauer spectroscopy measurements show a clear valence transition from approximately 50:50 Eu2+:Eu3+to fully Eu3+at ~28 GPa, consistent with the vanishing of the magnetic order at the same pressure. X-ray absorption data show a transition to a fully trivalent state at a similar pressure. Our results show that pressure first greatly enhancesTN, most likely via enhanced hybridization between the Eu 4fstates and the conduction band, and then, second, causes a structural phase transition that coincides with the conversion of the europium to a fully trivalent state. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, Advanced Materials)
    Abstract The hafnate perovskites PbHfO3(antiferroelectric) and SrHfO3(“potential” ferroelectric) are studied as epitaxial thin films on SrTiO3(001) substrates with the added opportunity of observing a morphotropic phase boundary (MPB) in the Pb1−xSrxHfO3system. The resulting (240)‐oriented PbHfO3(Pba2) films exhibited antiferroelectric switching with a saturation polarization ≈53 µC cm−2at 1.6 MV cm−1, weak‐field dielectric constant ≈186 at 298 K, and an antiferroelectric‐to‐paraelectric phase transition at ≈518 K. (002)‐oriented SrHfO3films exhibited neither ferroelectric behavior nor evidence of a polarP4mmphase . Instead, the SrHfO3films exhibited a weak‐field dielectric constant ≈25 at 298 K and no signs of a structural transition to a polar phase as a function of temperature (77–623 K) and electric field (–3 to 3 MV cm−1). While the lack of ferroelectric order in SrHfO3removes the potential for MPB, structural and property evolution of the Pb1−xSrxHfO3(0 ≤x < 1) system is explored. Strontium alloying increased the electric‐breakdown strength (EB) and decreased hysteresis loss, thus enhancing the capacitive energy storage density (Ur) and efficiency (η). The composition, Pb0.5Sr0.5HfO3produced the best combination ofEB = 5.12 ± 0.5 MV cm−1,Ur = 77 ± 5 J cm−3, and η = 97 ± 2%, well out‐performing PbHfO3and other antiferroelectric oxides. 
    more » « less
  4. ; ; ; ; ; ; ; ; ; ; et al (, Small)
    Abstract Iron rhodium (FeRh) undergoes a first‐order anti‐ferromagnetic to ferromagnetic phase transition above its Curie temperature. By measuring the anomalous Nernst effect (ANE) in (110)‐oriented FeRh films on Al2O3substrates, the ANE thermopower over a temperature range of 100–350 K is observed, with similar magnetic transport behaviors observed for in‐plane magnetization (IM) and out‐of‐plane magnetization (PM) configurations. The temperature‐dependent magnetization–magnetic field strength (M–H) curves revealed that the ANE voltage is proportional to the magnetization of the material, but additional features magnetic textures not shown in the M‐H curves remained intractable. In particular, a sign reversal occurred for the ANE thermopower signal near zero field in the mixed‐magnetic‐phase films at low temperatures, which is attributed to the diamagnetic properties of the Al2O3substrate. Finite element method simulations associated with the Heisenberg spin model and Landau–Lifshitz–Gilbert equation strongly supported the abnormal heat transport behavior from the Al2O3substrate during the experimentally observed magnetic phase transition for the IM and PM configurations. The results demonstrate that FeRh films on an Al2O3substrate exhibit unusual behavior compared to other ferromagnetic materials, indicating their potential for use in novel applications associated with practical spintronics device design, neuromorphic computing, and magnetic memory. 
    more » « less
  5. ; ; ; ; ; ; ; ; ; ; et al (, Journal of Physics: Condensed Matter)
    Abstract We study the effect of strain on the magnetic properties and magnetization configurations in nanogranular FexGe 1 − x films ( x = 0.53 ± 0.05 ) with and without B20 FeGe nanocrystals surrounded by an amorphous structure. Relaxed films on amorphous silicon nitride membranes reveal a disordered skyrmion phase while films near and on top of a rigid substrate favor ferromagnetism and an anisotropic hybridization of Fedlevels and spin-polarized Gespband states. The weakly coupled topological states emerge at room temperature and become more abundant at cryogenic temperatures without showing indications of pinning at defects or confinement to individual grains. These results demonstrate the possibility to control magnetic exchange and topological magnetism by strain and inform magnetoelasticity-mediated voltage control of topological phases in amorphous quantum materials. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email