Role of Ge in bridging ferromagnetism in the giant magnetocaloric Gd5(Ge1-xSix)4 alloys.
X-ray magnetic circular dichroism (XMCD) measurements and density functional theory (DFT) are used to study the electronic conduction states in Gd5(Ge(1-x)Si(x))4 materials through the first-order bond-breaking magnetostructural transition responsible for their giant magnetocaloric effect. Spin-dependent hybridization between Ge 4p and Gd 5d conduction states, which XMCD senses through the induced magnetic polarization in Ge ions, enables long-range Ruderman-Kittel-Kasuya-Yosida ferromagnetic interactions between Gd 4f moments in adjacent Gd slabs connected by Ge(Si) bonds. These interactions are strong below but weaken above the Ge(Si) bond-breaking transition that destroys 3D ferromagnetic order.
Haskel
D
D
Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Lee
Y B
YB
Harmon
B N
BN
Islam
Z
Z
Lang
J C
JC
Srajer
G
G
Mudryk
Ya
Y
Gschneidner
K A
KA
Pecharsky
V K
VK