Magnetic properties of icosahedral quasicrystals and their cubic approximants in the Cd–Mg–RE (RE = Gd, Tb, Dy, Ho, Er, and Tm) systems

Abstract

A systematic investigation has been performed to elucidate effects of Rare-Earth (RE) type and local atomic configuration on magnetic properties of icosahedral quasicrystal (iQC) and their cubic approximants (2/1 and 1/1 ACs) in the ternary Cd-Mg-RE (RE = Gd, Tb, Dy, Ho, Er, and Tm) systems. At low temperatures, iQC and 2/1 ACs exhibit spin-glass-like freezing for RE = Gd, Tb, Dy, and Ho, while Er and Tm systems do not show freezing behaviour down to the base temperature ~ 2 K. The 1/1 ACs exhibit either spin-glass-like freezing or antiferromagnetic (AFM) ordering depending on their constituent Mg content. The Tf values show increasing trend from iQC to 2/1 and 1/1 ACs. In contrast, the absolute values of Weiss temperature for iQCs are larger than those in 2/1 and 1/1 ACs, indicating that the total AFM interactions between the neighboring spins are larger in aperiodic, rather than periodic systems. Competing spin interactions originating from the long-range Ruderman-Kittel-Kasuya-Yoshida mechanism along with chemical disorder of Cd/Mg ions presumably account for the observed spin-glass-like behavior in Cd-Mg-RE iQCs and ACs.

Effects of Pt substitution on the formation and magnetic behavior of a Ga–Pd–Tb 2/1 approximant

“…Recently, diverse magnetic behaviors have been observed in Tsai-type 2/1 approximants, including ferromagnetic for (Au, Cu)-(Al, In)-R (R = Gd, Tb) [1], antiferromagnetic for Au-Ga-Eu [2] and Ga-Pd-Tb [3], and spin-glass-like for Cd-Mg-RE (RE = Gd, Tb, Dy, and Ho) [4] approximants. Compared to the 1/1 approximants, the 2/1 approximants are higher-order approximants, with larger unit cells, and are therefore considered a better approximation of the quasicrystal structure.…”

Memory and rejuvenation in a quasicrystal

“…It may be reasonable to expect magnetic frustration in such systems, owing to the symmetry, aperiodic structure and potential disorder in magnetic interaction. The magnetic interaction is often assumed to be of Ruderman-Kittel-Kasuya-Yosida (RKKY) type in the QCs and ACs [13,14].…”