Magnetic properties of icosahedral R–Mg–Zn quasicrystals (R=Y, Tb, Dy, Ho and Er)

• Published in: Journal of alloys and compounds 2000-05, Vol.303, p.223-227
• Main Authors: Fisher, I.R, Islam, Z, Zarestky, J, Stassis, C, Kramer, M.J, Goldman, A.I, Canfield, P.C
• Format: Article
• Language: English
• Subjects: Crystal growth; Magnetic measurements; Quasicrystals; Spin glass
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/S0925-8388(00)00635-6

Large (up to 0.5 cm 3) single grains of icosahedral R–Mg–Zn quasicrystals (R=Y, Tb, Dy, Ho and Er) have been grown via a self-flux technique. The samples have a composition of approximately R 9Mg 34Zn 57, and are extremely well-ordered, with little or no evidence of phason strain. These samples have allowed a detailed investigation of the magnetic behaviour of local 4 f moments in a quasiperiodic environment. Neutron scattering experiments using powdered single-grains show no evidence for long range magnetic order in the R–Mg–Zn quasicrystals. However, magnetization and magnetic susceptibility measurements indicate a spin-glass state, with freezing temperatures T f =5.8, 3.6, 2.0 and 1.3 K for R=Tb, Dy, Ho and Er respectively. Deviations from a Curie-Weiss temperature dependence of the susceptibility are small, and only occur for temperatures up to 5 K above T f , indicating the absence of any significant cluster glass behaviour. In addition, the rare earth dilution series (Y 1− x Gd x )–Mg–Zn have lower freezing temperatures than (Y 1− x Tb x )–Mg–Zn, despite the larger de Gennes factor of Gd 3+ over Tb 3+, indicating that crystal electric fields play a significant role in the freezing phenomenon. This difference between Heisenberg and non-Heisenberg moments is further explored via several (Gd 1− x R x )–Mg–Zn pseudo-ternary quasicrystal series.