Giant voltage-induced modification of magnetism in micron-scale ferromagnetic metals by hydrogen charging

Ye, Xinglong; Singh, Harish K.; Zhang, Hongbin; Geßwein, Holger; Chellali, Mohammed Reda; Witte, Ralf; Molinari, Alan; Skokov, Konstantin P.; Gutfleisch, Oliver; Hahn, Horst; Kruk, Robert

doi:10.1038/s41467-020-18552-z

Cited by 20 publications

(24 citation statements)

References 47 publications

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“…The working, the counter, and the reference electrodes were the Sm 2 Co 17 electrode, Pt wires, and a pseudo‐Ag/AgCl electrode, respectively. As established by Ye et al., [ 21 ] the used electrolyte was an aqueous electrolyte of 1 m KOH. The potential of the pseudo‐Ag/AgCl electrode is 0.300 ± 0.002 V more positive than the standard Hg/HgO (1 m KOH) electrode, and for comparison, all the voltages in were converted to the Hg/HgO scale.…”

Section: Methodsmentioning

confidence: 99%

“…In Situ XRD and SQUID Measurement: The crystal structure of the Sm 2 Co 17 electrode under the application of -1.2 and -0.4 V was monitored by in situ XRD with a parallel beam laboratory rotating anode diffractometer (Mo Kα radiation) in transmission geometry. The herein electrochemical setup is the same as that established by Ye et al, [21] only that the working electrode is replaced by the Sm 2 Co 17 electrode. Diffraction patterns were collected every 10 min with a Pilatus 300K-W area detector.…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, when the SmCo 5 phase was charged with hydrogen, its magnetocrystalline anisotropy was shown to decrease by ≈40%. [ 21 ] This further decreases the domain‐wall energy of the SmCo 5 phase and the nucleation field. Hydrogen segregation may also enlarge the transition region (Δ) between the GBs and the SmCo 5 phase with its continuous concentration change and reduce the nucleation field.…”

Section: Figurementioning

confidence: 99%

“…[16][17][18][19][20] In particular, the voltage-controlled hydrogen insertion/extraction into the crystal structure can substantially tune the coercivity of bulk ferromagnetic metallic materials such as the single-crystalline SmCo 5 . [21] Under voltage control, hydrogen atoms diffuse into the interstitial sites and modify the magnetocrystalline anisotropy drastically, which induces a change in coercivity. It is expected that in polycrystalline magnets, owing to the different trapping energy and mobility of hydrogen atoms to the different types of microstructural defects, hydrogen atoms would diffuse first along the grain boundaries, and then into the grain interiors.…”

mentioning

confidence: 99%

“…Here, by employing electrochemically controlled hydrogen charging/ discharging, [24] we tuned the coercivity of the Sm 2 Co 17 -based hard magnet by ≈1.3 T, the largest values ever achieved by magnetoelectric approaches. [16][17][18][19][20][21] The combined in-situ magneto-structural measurements and atomic-scale mapping of the hydrogen distribution [25][26][27] reveal that hydrogen atoms strongly segregate at grain boundaries, which weakens the local magnetic anisotropy and accounts for the predominant change in coercivity. Our study opens a way to achieve giant magnetoelectric effects through atomic-scale engineering of grain boundaries, and unveils the critical role of grain boundaries in limiting the performance of pinning-type magnets, a mechanism that can be exploited for future optimization strategies.…”

mentioning

confidence: 99%

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Magnetoelectric Tuning of Pinning‐Type Permanent Magnets through Atomic‐Scale Engineering of Grain Boundaries

Yan

Schäfer

et al. 2020

Advanced Materials

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a diameter less than ≈100 nm. After that, a cleaning of the specimen at 5 kV was performed to remove the beam-damaged surface regions. The prepared tips were transferred into the load-lock chamber of APT, waited ≈2 h until the vacuum reached ≈10 −8 Pa (LEAP 3000 XHR), and then transferred into analysis chamber (≈10 −11 Pa) at 70 K. Data on Cameca LEAP 5000XR were also acquired, and only waited for half an hour before transferring the sample from APT load-lock to analysis chamber. The APT experiments were conducted using high-voltage mode with a pulse fraction of 15% at a base temperature of 70 K, a pulse frequency of 200 kHz, and an evaporation rate of 0.5. Atom probe data reconstruction and analysis were performed using CAMECA IVAS 3.8.4 software.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Magnetoelectric Tuning of Pinning‐Type Permanent Magnets through Atomic‐Scale Engineering of Grain Boundaries

Yan

Schäfer

et al. 2020

Advanced Materials

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Magneto‐Ionic Control of Coercivity and Domain‐Wall Velocity in Co/Pd Multilayers by Electrochemical Hydrogen Loading

Bischoff,

Ehrler,

Engelhardt

et al. 2024

Adv Funct Materials

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Magneto‐ionics, as the electrochemical reconfiguration of magnetic materials at low gating voltages, is a highly energy‐efficient alternative to control magnetism. For the fastest magneto‐ionic concept based on hydrogen, fundamental mechanisms are currently under debate, mainly because quantitative compositional information inside the magnetic materials upon gating is lacking. Using the electrochemical hydrogen loading of Co/Pd multilayers with perpendicular anisotropy, this study demonstrates that the hydrogen concentration inside the magnetic material determines its magnetic properties. Hydrogen concentrations up to a maximum of (0.24 ± 0.01) hydrogen atoms per metal atom can be set deterministically by voltage and are quantified via flow‐cell coulometry. With increasing hydrogen concentration, a continuous increase in coercivity of up to 15% and a decrease in magnetic domain‐wall velocity by an order of magnitude are observed using in situ MOKE microscopy. This enables the voltage‐controlled stop‐and‐go of domain walls. These magneto‐ionic effects can be explained by an increasing perpendicular anisotropy with increasing hydrogen content in Co/Pd multilayers, which is supported by theory. Importantly, the approach should be transferable to other ionic systems, such as lithium‐ or oxygen‐based ones, where it can uncover the yet hidden effects of ionic concentration on the magnetic properties and guide the design of functional magneto‐ionic devices.

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Space‐Charge Control of Magnetism in Ferromagnetic Metals: Coupling Giant Magnitude and Robust Endurance

Liu

Zhao

et al. 2022

Advanced Materials

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ensures the excellent performance of spin-based devices at room temperature. [5][6][7] Taking advantage of the intrinsic coupling of electricity and magnetism, multiferroics and magnetoelectrics favor a modulation via exchange interaction with metals. [3,[8][9][10] However, there is currently a dearth of technologically viable multiferroics that exhibit strong magnetoelectric (ME) coupling at room temperature. [11,12] A broader available option, high dielectric gates (MgO, HfO 2 , AlO x , etc.) are typically used to manipulate charge-related magnetism in ultra-thin FM-metal systems, such as Co/HfO 2 , [13] FeCo/MgO and Fe/MgO junctions. [14][15][16] This charge doping method can change the density of the itinerant electrons in a ferromagnet, thus further manipulating magnetocrystalline anisotropy. [17][18][19] Although this allows for an ultra-fast modulation with a lifespan beyond 10 4 cycles, the volatile and small magnitude of modulation limit its application. [12,[19][20][21] The quest for realizing a modulation of magnetism in metals, where a low power-consumption is accompanied with a large-amplitude modulation, high reversibility, fast switching speed and room temperature, has been continuously explored (some representative works are summarized in Table S1, Supporting Information).The pursuit of enormous manipulation effects (e.g., magnetiza tion, magnetic phase) has encouraged the emergence Ferromagnetic metals show great prospects in ultralow-power-consumption spintronic devices, due to their high Curie temperature and robust magnetization. However, there is still a lack of reliable solutions for giant and reversible voltage control of magnetism in ferromagnetic metal films. Here, a novel space-charge approach is proposed which allows for achieving a modulation of 30.3 emu/g under 1.3 V in Co/TiO 2 multilayer granular films. The robust endurance with more than 5000 cycles is demonstrated. Similar phenomena exist in Ni/TiO 2 and Fe/TiO 2 multilayer granular films, which shows its universality. The magnetic change of 107% in Ni/TiO 2 underlines its potential in a voltage-driven ON-OFF magnetism. Such giant and reversible voltage control of magnetism can be ascribed to space-charge effect at the ferromagnetic metals/TiO 2 interfaces, in which spin-polarized electrons are injected into the ferromagnetic metal layer with the adsorption of lithium-ions on the TiO 2 surface. These results open the door for a promising method to modulate the magnetization in ferromagnetic metals, paving the way toward the development of ionic-magnetic-electric coupled applications.

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Giant voltage-induced modification of magnetism in micron-scale ferromagnetic metals by hydrogen charging

Cited by 20 publications

References 47 publications

Magnetoelectric Tuning of Pinning‐Type Permanent Magnets through Atomic‐Scale Engineering of Grain Boundaries

Magnetoelectric Tuning of Pinning‐Type Permanent Magnets through Atomic‐Scale Engineering of Grain Boundaries

Magneto‐Ionic Control of Coercivity and Domain‐Wall Velocity in Co/Pd Multilayers by Electrochemical Hydrogen Loading

Space‐Charge Control of Magnetism in Ferromagnetic Metals: Coupling Giant Magnitude and Robust Endurance

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