The impact of deposition temperature on L1 formation in FePt films

Wang, Bincheng; Barmak, K.

doi:10.1063/1.3679388

Cited by 7 publications

(3 citation statements)

References 17 publications

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“…It is to be noted that usually in FePt alloys, temperatures higher than 550 °C are needed in order to promote the formation of the L1 0 phase, and this value is even higher in the case of FePt nanoparticles. To our knowledge, incipient formation of the L1 0 phase at temperatures lower than 400 °C (around 300 °C) has only been reported by Wang and Barmak [ 42 ] in ultrathin FePt films co-sputtered on hot substrates. Two more inflection points, signaled by arrows on the graph, are observed on the hysteresis loop.…”

Section: Resultsmentioning

confidence: 92%

Magnetic Phase Coexistence and Hard–Soft Exchange Coupling in FePt Nanocomposite Magnets

et al. 2020

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With the aim of demonstrating phase coexistence of two magnetic phases in an intermediate annealing regime and obtaining highly coercive FePt nanocomposite magnets, two alloys of slightly off-equiatomic composition of a binary Fe-Pt system were prepared by dynamic rotation switching and ball milling. The alloys, with a composition Fe53Pt47 and Fe55Pt45, were subsequently annealed at 400 °C and 550 °C and structurally and magnetically characterized by means of X-ray diffraction, 57Fe Mössbauer spectrometry and Superconducting Quantum Interference Device (SQUID) magnetometry measurements. Gradual disorder–order phase transformation and temperature-dependent evolution of the phase structure were monitored using X-ray diffraction of synchrotron radiation. It was shown that for annealing temperatures as low as 400 °C, a predominant, highly ordered L10 phase is formed in both alloys, coexisting with a cubic L12 soft magnetic FePt phase. The coexistence of the two phases is evidenced through all the investigating techniques that we employed. SQUID magnetometry hysteresis loops of samples annealed at 400 °C exhibit inflection points that witness the coexistence of the soft and hard magnetic phases and high values of coercivity and remanence are obtained. For the samples annealed at 500 °C, the hysteresis loops are continuous, without inflection points, witnessing complete exchange coupling of the hard and soft magnetic phases and further enhancement of the coercive field. Maximum energy products comparable with values of current permanent magnets are found for both samples for annealing temperatures as low as 500 °C. These findings demonstrate an interesting method to obtain rare earth-free permanent nanocomposite magnets with hard–soft exchange-coupled magnetic phases.

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Section: Resultsmentioning

confidence: 92%

Magnetic Phase Coexistence and Hard–Soft Exchange Coupling in FePt Nanocomposite Magnets

et al. 2020

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“…Differential scanning calorimetry (DSC) studies of the A1 to L1 0 transformation in FePt By preparing suitable samples, i.e., films that are thick enough to provide several milligrams when lifted off the substrate, phase transformations in thin metallic films can be investigated by differential scanning calorimetry (DSC) [24][25][26][27][28][29][30][31][32][33][34]. Michaelsen et al [24] provide a detailed review of sample 7.2 Example DSC traces for a binary Fe 51.4 Pt 48.6 film.…”

Section: 4mentioning

confidence: 99%

Disorder–order transformations in metallic films

Barmak

2014

Metallic Films for Electronic, Optical and Magnetic Applications

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“…• C is usually required (alternatively high deposition temperatures may be used [3]). High temperature processes are not however attractive for industrial production processes, and high temperature treatments also typically lead to both grain size and exchange coupling increases [4] which are unfavourable for obtaining high recording density and high signal-to-noise ratios.…”

Section: Introductionmentioning

confidence: 99%

Suppressed silicide formation in FePt thin films by nitrogen addition

Tran

Wright

2013

Journal of Magnetism and Magnetic Materials

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FePt and FePtN thin films have been prepared on silicon substrates by the relatively new deposition technique known as High Target Utilisation Sputtering. Films were annealed postdeposition at temperatures up to 8000C in order to induce the high-anisotropy L10 phase. The FePt films initially showed an improvement in magnetic properties with annealing temperature, but for annealing above around 400 •C the magnetic properties deteriorated markedly. The magnetic properties of the FePtN films, however, continued to improve with increasing annealing temperature, right up to the maximum temperature applied of 800 •C. Analysis by x-ray diffraction revealed the formation of iron and platinum silicides in FePt films above 400 •C, but that such silicides are absent from the FePtN at all annealing temperatures except 800 •C. This behaviour is attributed to the nitrogen in FePtN films reacting preferentially with the silicon in the substrate to form silicon nitride, thus suppressing the formation of platinum and iron silicides. Thus, by introducing nitrogen during the deposition of FePt films on Si substrates th formation of deleterious silicides appears to be suppressed during thermal treatment, thereby offering protection against silicon pollution. • C in order to induce the high-anisotropy L1 0 phase. The FePt films initially showed an improvement in magnetic properties with annealing temperature, but for annealing above around 400• C the magnetic properties deteriorated markedly. The magnetic properties of the FePtN films, however, continued to improve with increasing annealing temperature, right up to the maximum temperature applied of 800• C. Analysis by x-ray diffraction revealed the formation of iron and platinum silicides in FePt films above 400• C, but that such silicides are absent from the FePtN at all annealing temperatures except 800• C. This behaviour is attributed to the nitrogen in FePtN films reacting preferentially with the silicon in the substrate to form silicon nitride, thus suppressing the formation of platinum and iron silicides. Thus, by introducing nitrogen during the deposition of FePt films on Si substrates the formation of deleterious silicides appears to be suppressed during thermal treatment, thereby offering protection against silicon pollution.

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The impact of deposition temperature on L1 formation in FePt films

Cited by 7 publications

References 17 publications

Magnetic Phase Coexistence and Hard–Soft Exchange Coupling in FePt Nanocomposite Magnets

Magnetic Phase Coexistence and Hard–Soft Exchange Coupling in FePt Nanocomposite Magnets

Disorder–order transformations in metallic films

Suppressed silicide formation in FePt thin films by nitrogen addition

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