Making and breaking covalent bonds across the magnetic transition in the giant magnetocaloric material Gd-5(Si2Ge2)

Authors
Choe, W Pecharsky, VK Pecharsky, AO Gschneidner, KA Young, VG Miller, GJ
Citation
W. Choe et al., Making and breaking covalent bonds across the magnetic transition in the giant magnetocaloric material Gd-5(Si2Ge2), PHYS REV L, 84(20), 2000, pp. 4617-4620
Citations number
20
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW LETTERS
ISSN journal
00319007 → ACNP
Volume
84
Issue
20
Year of publication
2000
Pages
4617 - 4620
Database
ISI
SICI code
0031-9007(20000515)84:20<4617:MABCBA>2.0.ZU;2-E
Abstract
A temperature-dependent, single crystal x-ray diffraction study of the gian t magnetocaloric material, Gd-5(Si2Ge2), across its Curie temperature (276 K) reveals that the simultaneous orthorhombic to monoclinic transition occu rs by a shear mechanism in which the (Si, Ge)-(Si, Ge) dimers that are rich er in Ge increase their distances by 0.859(3) if and lead to twinning. The structural transition changes the electronic structure, and provides an ato mic-level model for the change in magnetic behavior with temperature in the Gd-5(SixGe1-x)(4).