Correlation between phase transition characteristics and hydrogen irradiation-induced Frenkel defect formations in FeRh films

Song, Sehwan; Cho, Chang-woo; Kim, Jiwoong; Lee, Jisung; Lee, Dooyong; Kim, Doukyun; Kim, Hyegyoung; Kang, Haeyong; Park, Chul‐Hong; Park, Jun Kue; Jang, Jae Hyuck; Park, Sungkyun

doi:10.1016/j.jallcom.2022.163611

Cited by 6 publications

(2 citation statements)

References 66 publications

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“…2 d we plot the saturation magnetisation M sat extracted from the SQUID data below T (AF−F M ) and show that it increases slightly as we decrease the temperature below T ≈ 200 K. The data shown in Fig. 2 d is normalised by the total volume of FeRh, but even considering the normalisation by the effective volume of the ferromagnetic interfaces with a combined thickness of 10 nm, M sat in the AF phase remains significantly smaller than M sat for FM-FeRh, in agreement with previous studies 1 , 32 – 34 . We reproduce the temperature dependence of the magnetisation via atomistic spin dynamics simulations considering a monolayer of FM-FePd in contact with AF-FeRh, as discussed in more detail in section S2 B.…”

Section: Resultssupporting

confidence: 90%

Ultra-high spin emission from antiferromagnetic FeRh

Hamara,

Strungaru,

Massey

et al. 2024

Nat Commun

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An antiferromagnet emits spin currents when time-reversal symmetry is broken. This is typically achieved by applying an external magnetic field below and above the spin-flop transition or by optical pumping. In this work we apply optical pump-THz emission spectroscopy to study picosecond spin pumping from metallic FeRh as a function of temperature. Intriguingly we find that in the low-temperature antiferromagnetic phase the laser pulse induces a large and coherent spin pumping, while not crossing into the ferromagnetic phase. With temperature and magnetic field dependent measurements combined with atomistic spin dynamics simulations we show that the antiferromagnetic spin-lattice is destabilised by the combined action of optical pumping and picosecond spin-biasing by the conduction electron population, which results in spin accumulation. We propose that the amplitude of the effect is inherent to the nature of FeRh, particularly the Rh atoms and their high spin susceptibility. We believe that the principles shown here could be used to produce more effective spin current emitters. Our results also corroborate the work of others showing that the magnetic phase transition begins on a very fast picosecond timescale, but this timescale is often hidden by measurements which are confounded by the slower domain dynamics.

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Section: Resultssupporting

confidence: 90%

Ultra-high spin emission from antiferromagnetic FeRh

Hamara,

Strungaru,

Massey

et al. 2024

Nat Commun

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“…Furthermore, the decrease in mode intensity around 667 cm –1 may reflect the removal of O-atoms. Irradiation causes Frenkel defect, which is a vacancy and an interstitial pair . These defects cause crystallinity to deteriorate, and sometimes the peak intensity goes down. , The low-intensity modes at 929 cm –1 are likely to be related to H–Ti–O symmetric stretching mode with a very tiny Ti–O separation and four-coordinate Ti–O vibration in the H 2 Ti 3 O 7 phase …”

Section: Resultsmentioning

confidence: 99%

Core–Shell Nanostructures of Tungsten Oxide and Hydrogen Titanate for H₂ Gas Adsorption

Rajbhar

Das

Möller

et al. 2022

ACS Appl. Nano Mater.

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Nanostructured tungsten oxide is a promising material for sensing reducing gases such as hydrogen. However, this material exhibits limitations due to a poor response toward sensing at room temperature, incomplete recovery to the initial state, long response time, and a low response factor, which is not desired for explosive gases like hydrogen. In this work, we, for the first time, demonstrate that these limitations can be significantly overcome using the core–shell structure of tungsten oxide (WO3) nanorods and hydrogen titanate (H2Ti3O7) nanotubes developed and suitably defect-engineered by low-energy ion irradiation. The sensor based on the pristine core–shell heterostructure of tungsten oxide nanorods and hydrogen titanate nanotubes exhibits excellent response and selectivity to different concentrations of H2 ranging from 10 to 500 ppm. However, it requires a quite high temperature of 300 °C with response and recovery times of about 38 and 99.8 s, respectively. After irradiation, the hybrid form shows a similar level of response and selectivity, however, at a much lower temperature of about 120 °C with significantly faster response and recovery times of about 16 and 18 s, respectively. Such an ion beam-modified structure addresses critical issues of developing a gas-sensing device, such as the effects of moisture and power consumption. The experimental observations are very well in agreement with the predictions of the state-of-the-art Monte Carlo-based TRI3DYN ion-solid interaction simulation, and the gas-sensing mechanism was explained using first principles-based calculation. The study reveals that low-energy ion-induced defect engineering yields better charge transport, better binding of the gas with the surface, as well as the superior moisture-repelling ability of the surface, leading to better sensing performance than the pristine core-shell structure. This heterostructure between two nanomaterials carries complementary advantages in various aspects, such as the surface area, conductivity, and sensitivity toward a wide range and mixture of gases. Additionally, the wrapping yields good mechanical strength and flexibility, making it possible to use as a flexible sensing device made through a bottom-up fabrication technique.

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Abnormal Magnetic Phase Transition in Mixed‐Phase (110)‐Oriented FeRh Films on Al₂O₃ Substrates via the Anomalous Nernst Effect

Choi,

Park,

Kim

et al. 2024

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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 Al2O3 substrates, 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 Al2O3 substrate. Finite element method simulations associated with the Heisenberg spin model and Landau–Lifshitz–Gilbert equation strongly supported the abnormal heat transport behavior from the Al2O3 substrate during the experimentally observed magnetic phase transition for the IM and PM configurations. The results demonstrate that FeRh films on an Al2O3 substrate 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.

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Correlation between phase transition characteristics and hydrogen irradiation-induced Frenkel defect formations in FeRh films

Cited by 6 publications

References 66 publications

Ultra-high spin emission from antiferromagnetic FeRh

Ultra-high spin emission from antiferromagnetic FeRh

Core–Shell Nanostructures of Tungsten Oxide and Hydrogen Titanate for H₂ Gas Adsorption

Abnormal Magnetic Phase Transition in Mixed‐Phase (110)‐Oriented FeRh Films on Al₂O₃ Substrates via the Anomalous Nernst Effect

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Correlation between phase transition characteristics and hydrogen irradiation-induced Frenkel defect formations in FeRh films

Cited by 6 publications

References 66 publications

Ultra-high spin emission from antiferromagnetic FeRh

Ultra-high spin emission from antiferromagnetic FeRh

Core–Shell Nanostructures of Tungsten Oxide and Hydrogen Titanate for H2 Gas Adsorption

Abnormal Magnetic Phase Transition in Mixed‐Phase (110)‐Oriented FeRh Films on Al2O3 Substrates via the Anomalous Nernst Effect

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Product

Resources

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Core–Shell Nanostructures of Tungsten Oxide and Hydrogen Titanate for H₂ Gas Adsorption

Abnormal Magnetic Phase Transition in Mixed‐Phase (110)‐Oriented FeRh Films on Al₂O₃ Substrates via the Anomalous Nernst Effect