Discovery of spin glass behavior in Ln 2Fe 4Sb 5 (Ln = La-Nd and Sm)

W. Adam Phelan, Louisiana State University
Giang V. Nguyen, Louisiana State University
Jiakui K. Wang, Rice University
Gregory T. McCandless, Louisiana State University
Emilia Morosan, Rice University
John F. Ditusa, Louisiana State University
Julia Y. Chan, Louisiana State University


Single crystals of Ln 2Fe 4Sb 5 (Ln = La-Nd and Sm) were grown from an inert Bi flux. Measurements of the single crystal X-ray diffraction revealed that these compounds crystallize in the tetragonal space group I4/mmm with lattice parameters of a ≈ 4 Å, c ≈ 26 Å, V ≈ 500 Å 3, and Z = 2. This crystal structure consists of alternating LnSb 8 square antiprisms and Fe-sublattices composed of nearly equilateral triangles of bonded Fe atoms. These compounds are metallic and display spin glass behavior, which originates from the magnetic interactions within the Fe-sublattice. Specific heat measurements are void of any sharp features that can be interpreted as contributions from phase transitions as is typical for spin glass systems. A large, approximately linear in temperature, contribution to the specific heat of La 2Fe 4Sb 5 is observed at low temperatures that we interpret as having a magnetic origin. Herein, we report the synthesis, structure, and physical properties of Ln 2Fe 4Sb 5 (Ln = La-Nd and Sm). © 2012 American Chemical Society.