Abstract

The use of hydrogen atoms for magneto-ionic applications has only been explored recently. Benefits of hydrogen compared to other ionic species for tuning magnetism are high switching speed and large changes in magnetic moment. Here, we test the influence of hydrogen intercalation on magnetism in nanoporous Pd(1−x)Cox, with Co being located in superparamagnetic clusters, building upon a previously suggested material system. Tailoring the Co concentration and distribution allows the magnitude of the magneto-electric effect to be influenced as well as to gain a deeper understanding of the interaction of hydrogen with magnetic clusters. In situ magnetization measurements are conducted to directly observe the variation in magnetic moment upon hydrogen-charging in nanoporous Pd(1−x)Cox. Temperature-dependent magnetization curves show that interstitial hydrogen atoms lead to an increase in magnetic anisotropy energy, a coupling of individual Co-rich clusters, and the concomitant blocking of their magnetic moments. The large obtained magnetic switching effects upon hydrogen-charging at room temperature (αC,V > 400 Oe V−1; ΔM = 1.5 emu g−1) open up new possibilities to use magneto-ionic effects for real-life applications in magnetic devices.

Highlights

  • Hydrogen, as the smallest atom in the Periodic Table, is able to form interstitial compounds with several metals and alloys

  • A hydrogen atom on an interstitial site donates its electron into the bands of the host material, raising the Fermi energy and changing the density of states at the Fermi level

  • We analyzed the effect of Co-concentration in npPd(1−x)Cox on the magnetic tuning response upon hydrogen charging

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Summary

INTRODUCTION

As the smallest atom in the Periodic Table, is able to form interstitial compounds with several metals and alloys. As the smallest atom, is able to form interstitial compounds with several metals and alloys They are attractive as a safe method for hydrogen storage but can be used to alter electrical, optical, or magnetic properties of the host materials. A rather young field of research built upon such electrochemical reactions is the controlled tuning of magnetic properties, termed magneto-ionics.. Considering the importance of superparamagnetic Co-rich clusters for the switching mechanism, we expect a strong influence of cluster size and distribution on the magneto-ionic effect. This allows additional insights into the magneto-ionic tuning mechanism and the interaction of hydrogen with superparamagnetic clusters

EXPERIMENTAL
SAMPLE PREPARATION—GALVANODYNAMICALLY CONTROLLED DEALLOYING
Variation of magnetization with Co content
Variation of magnetic cluster size with Co content
Discussion
CONCLUSION
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