Strong room-temperature easy-axis anisotropy in Tb2Fe17H3: An exception among R2Fe17 hydrides


Strong room-temperature easy-axis anisotropy in Tb2Fe17H3: An exception among R2Fe17 hydrides

Tereshina, E. A.; Drulis, H.; Skourski, Y.; Tereshina, I. S.

The iron-rich intermetallics R 2Fe17 (where R is a rare-earth element) proved unamenable to anisotropy control via interstitial doping. There is only one precedent, Sm2Fe17N3−δ (Sm2Fe17C3−δ ), where interstitial modification has stabilized an easy-axis anisotropy at all temperatures up to TC. All previous attempts to prepare a usable easy-axisR2Fe17 hydride have failed. Now we have succeeded in preparing a high-quality single-phase Tb2Fe17H3 single crystal,which has the required easy-axis anisotropy between 0 K and TC =560 K. At T =300 K, Tb2Fe17H3 has the spontaneous magnetic moment Ms of 22.5 μB per formula unit and anisotropy field μ0Ha of 2.5 T. The main mechanism stabilizing the easy-axis anisotropy in hydrides is the same as in other similar compounds by way of boosting the leading crystal field parameter A20. Terbium is rather special in having the Stevens factors such that αJ < 0 and βJ > 0, which is why the easy-axis anisotropy in Tb2Fe17 hydrides is also assisted by the fourth-order parameter A40. This proves a decisive advantage over the compounds with R = Pr, Nd, Dy, or Ho where βJ < 0 and A40 is a hindrance.

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Publ.-Id: 19391