Magnetic ordering temperature of nanocrystalline Gd: enhancement of magnetic interactions via hydrogenation-induced “negative” pressure
Abstract
Gadolinium
is a nearly ideal soft-magnetic material. However, one cannot take
advantage of its properties at temperatures higher than the room
temperature where Gd loses the ferromagnetic ordering. By using
high-purity bulk samples with grains ~200 nm in size, we present
proof-of-concept measurements of an increased Curie point (TC) and spontaneous magnetization in Gd due to hydrogenation. From first-principles we explain increase of TC
in pure Gd due to the addition of hydrogen. We show that the interplay
of the characteristic features in the electronic structure of the
conduction band at the Fermi level in the high-temperature paramagnetic
phase of Gd and “negative” pressure exerted by hydrogen are responsible
for the observed effect.
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