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.
Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
D
D
Haskel
Y B
YB
Lee
B N
BN
Harmon
Z
Z
Islam
J C
JC
Lang
G
G
Srajer
Ya
Y
Mudryk
K A
KA
Gschneidner
V K
VK
Pecharsky