Open volume defects and magnetic phase transition in Fe60Al40 transition metal aluminide

Liedke, Maciej Oskar; Anwand, W.; Bali, Rantej; Cornelius, S.; Butterling, Maik; Trinh, Thu Trang; Wagner, A.; Salamon, Soma; Walecki, D.; Smekhova, A.; Wende, Heiko; Potzger, К.

doi:10.1063/1.4919014

Cited by 69 publications

(49 citation statements)

References 22 publications

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“…The deposition was performed using a target of the same Fe-rich composition. Annealing in vacuum at 773K for 1 h leads to the formation of the chemically ordered B2 phase that was confirmed by the observed superlattice (100) XRD peak [8,36]. The native oxide SiO 2 buffer layer was used to prevent an unfavorable silicide formation at the Fe 60 Al 40 /Si interface during the annealing process.…”

Section: A Samplesmentioning

confidence: 86%

Local probe of irradiation-induced structural changes and orbital magnetism in Fe60Al40 thin films via an order-disorder phase transition

et al. 2018

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Hard x-ray absorption and magnetic circular dichroism spectroscopy have been applied to study the consequential changes of the local environment around Fe atoms and their orbital polarizations in 40 nm thick Fe 60 Al 40 thin films along the order-disorder (B2 → A2) phase transition initiated by 20-keV Ne + ion irradiation with fluences of (0.75-6) ×10 14 ions cm −2. The analysis of the extended x-ray absorption fine structure spectra measured at the Fe K edge at room temperature revealed an increased number of Fe-Fe nearest neighbors from 3.47(7) to 5.0(1) and ∼1% of volume expansion through the transition. The visualization of the Fe and Al nearest-neighbor rearrangement in the first coordination shell of Fe absorbers via the transition was carried out by wavelet transformations. The obtained changes in Fe coordination are evidently reflected in the x-ray magnetic circular dichroism spectra which show an increased orbital magnetic moment of Fe atoms and a pronounced magnetic multielectronic excitations peak at ∼60 eV above the edge. The amplitudes of both peaks demonstrated similar dependencies on the irradiation fluence. The results of self-consistent density functional calculations on relaxed Fe 60 Al 40 model structures for the ordered (B2) and the disordered (A2) phases are consistent with the experimental findings and point to the formation of Fe-rich regions in the films studied.

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Section: A Samplesmentioning

confidence: 86%

Local probe of irradiation-induced structural changes and orbital magnetism in Fe60Al40 thin films via an order-disorder phase transition

et al. 2018

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“…Due to the momentum of the electrons, the variation from that value is a result of Doppler broadening (DB) of the annihilation line. The Doppler broadening is characterized by the shape parameter Q and the wing parameter R. More details about both parameters can be found elsewhere 47,48…”

Section: Positron Annihilation Spectroscopymentioning

confidence: 99%

Purely antiferromagnetic magnetoelectric random access memory

et al. 2017

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Magnetic random access memory schemes employing magnetoelectric coupling to write binary information promise outstanding energy efficiency. We propose and demonstrate a purely antiferromagnetic magnetoelectric random access memory (AF-MERAM) that offers a remarkable 50-fold reduction of the writing threshold compared with ferromagnet-based counterparts, is robust against magnetic disturbances and exhibits no ferromagnetic hysteresis losses. Using the magnetoelectric antiferromagnet Cr2O3, we demonstrate reliable isothermal switching via gate voltage pulses and all-electric readout at room temperature. As no ferromagnetic component is present in the system, the writing magnetic field does not need to be pulsed for readout, allowing permanent magnets to be used. Based on our prototypes, we construct a comprehensive model of the magnetoelectric selection mechanisms in thin films of magnetoelectric antiferromagnets, revealing misfit induced ferrimagnetism as an important factor. Beyond memory applications, the AF-MERAM concept introduces a general all-electric interface for antiferromagnets and should find wide applicability in antiferromagnetic spintronics.

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“…As a precursor for the MePS installation a pre-stage of AIDA has been implemented at the SPONSOR beam and in-situ experiments on the influence of defects on magnetic phase transitions in Fe 60 Al 40 alloys [16] and on Cr 2 O 3 which is used in a purely antiferromagnetic magneto-electric random access memory have been performed [17]. As an exemplary result figure 7, (b) shows the energy-dependent shape parameter variations for thin Fe 60 Al 40 films after in-situ temperature treatments.…”

Section: The Apparatus For In-situ Defect Analysis (Aida)mentioning

confidence: 99%

Positron annihilation lifetime and Doppler broadening spectroscopy at the ELBE facility

Wagner

Butterling

Liedke

et al. 2018

AIP Conference Proceedings

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The Helmholtz-Zentrum Dresden-Rossendorf operates a superconducting linear accelerator for electrons with energies up to 35 MeV and average beam currents up to 1.6 mA with bunch charges up to 120 pC. The electron beam is employed to produce several secondary beams including X-rays from bremsstrahlung production, coherent IR light in a Free Electron Laser, superradiant THz radiation, neutrons, and positrons. The secondary positron beam after moderation feeds the Monoenergetic Positron Source (MePS) where positron annihilation lifetime (PALS) and positron annihilation Doppler-broadening experiments in materials science are performed. The adjustable repetition rate of the continuouswave electron beams allows matching of the pulse separation to the positron lifetime in the sample under study. The energy of the positron beam can be set between 0.5 keV and 20 keV to perform depth resolved defect spectroscopy and porosity studies especially for thin films. Bulk materials, fluids, gases, and even radioactive samples can be studied at the unique Gamma-induced Positron Source (GiPS) where an intense bremsstrahlung source generates positrons directly inside the material under study. A 22 Na-based monoenergetic positron beam serves for offline experiments and additional depth-resolved Doppler-broadening studies complementing both accelerator-based sources.

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Open volume defects and magnetic phase transition in Fe60Al40 transition metal aluminide

Cited by 69 publications

References 22 publications

Local probe of irradiation-induced structural changes and orbital magnetism in Fe60Al40 thin films via an order-disorder phase transition

Local probe of irradiation-induced structural changes and orbital magnetism in Fe60Al40 thin films via an order-disorder phase transition

Purely antiferromagnetic magnetoelectric random access memory

Positron annihilation lifetime and Doppler broadening spectroscopy at the ELBE facility

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