Ferromagnetism and re-entrant spin-glass transition in quasicrystal approximants Au-SM-Gd (SM = Si, Ge).
Magnetic susceptibility and specific heat measurements on quasicrystalline approximants Au-Si-Gd and Au-Ge-Gd reveal that a ferromagnetic (FM) transition occurs at Tc = 22.5(5) K for Au-Si-Gd and at Tc = 13(1) K for Au-Ge-Gd, which are the first examples of ferromagnetism in crystalline approximants. In addition, a re-entrant spin-glass (RSG) transition is observed at TRSG = 3.3 K for Au-Ge-Gd in contrast to Au-Si-Gd. The different behaviors are understood based on the recent structural models reported by Gebresenbut et al (2013 J. Phys.: Condens. Matter 25 135402). The RSG transition in Au-Ge-Gd is attributed to a random occupation of the center of the Gd12 icosahedron by Gd atoms; a central Gd spin hinders the long-range FM order.
Department of Materials Science and Technology, Tokyo University of Science, Niijuku, Tokyo 125-8585, Japan.
T
T
Hiroto
G H
GH
Gebresenbut
C
C
Pay Gómez
Y
Y
Muro
M
M
Isobe
Y
Y
Ueda
K
K
Tokiwa
R
R
Tamura