Structural and magnetic properties ofGd5SixSn4−x

Abstract

The ternary ${\mathrm{Gd}}_{5}{\mathrm{Si}}_{x}{\mathrm{Sn}}_{4\ensuremath{-}x}$ alloy system has been shown to exist for all x. Structural and magnetic phase diagrams have been derived. Si-rich and Sn-rich alloys are orthorhombic and order ferromagnetically, with ${T}_{c}$ increasing with Si content. Intermediate compositions are monoclinic, and exhibit a disordered noncollinear magnetic order. In the ordered state, ${}^{119}\mathrm{Sn}$ M\ossbauer spectroscopy shows transferred hyperfine fields approaching 37 T at Sn sites in the orthorhombic form, and severely broadened spectra with much smaller fields in the monoclinic form. For $xl~0.4,$ there is, on heating, a first-order magnetic and structural transition from a ferromagnetic to a nonmagnetic state that may be associated with a giant magnetocaloric effect.