Making and breaking covalent bonds across the magnetic transition in the giant magnetocaloric material Gd5(Si2Ge2)
A temperature-dependent, single crystal x-ray diffraction study of the giant magnetocaloric material, Gd5(Si2Ge2), across its Curie temperature (276 K) reveals that the simultaneous orthorhombic to monoclinic transition occurs by a shear mechanism in which the (Si, Ge)-(Si,Ge) dimers that are richer in Ge increase their distances by 0.859(3) A and lead to twinning. The structural transition changes the electronic structure, and provides an atomic-level model for the change in magnetic behavior with temperature in the Gd5(SixGe1-x)(4).
Choe
W
Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Pecharsky
VK
Pecharsky
AO
Gschneidner
KA
Young
VG
Miller
GJ