Competition between spin-glass and antiferromagnetic states in Tsai-type 1/1 and 2/1 quasicrystal approximants

Abstract

Systematic research was performed to investigate magnetic properties of the Tsai-type Ga-Pd-RE (RE = Gd, Tb, Dy, and Ho) systems, where both 1/1 and 2/1 quasicrystal approximants (ACs) are attainable at the same compositions as thermodynamical stable phases. Most of the samples exhibited spin-glass (SG)-like freezing behavior at low temperatures except Ga-Pd-Tb 2/1 AC and Ga-Pd-Ho 1/1 AC. The former showcased antiferromagnetic order at 5.78 K while the latter did not show any anomaly down to 1.8 K. Furthermore, 2/1 ACs were noticed to be less frustrated than their corresponding 1/1 ACs presumably due to the disorder-free environment in the nearest neighbors of the rare earth sites that form a network of distorted octahedron in the 2/1 ACs. The spin dynamic in SG samples was also characterized by means of ac magnetic susceptibility measurements. The results evidenced a weak response of the freezing temperatures to the measurement frequency in the Heisenberg systems, i.e., Gd-contained ACs, in contrast to the non-Heisenberg systems, i.e., Tb, Dy and Ho-contained ACs, where significant dependency is noticed for the latter. The spin-glass samples were further examined by fitting their freezing temperatures to the Vogel-Fulcher law.