Structural-transition-driven antiferromagnetic to spin-glass transition in Cd–Mg–Tb 1/1 approximants

Abstract

The magnetic susceptibility of the quasicrystal 1/1 approximants in a series of 10,15,20) alloys was investigated in detail. The occurrence of antiferromagnetic (AFM) to spin-glass (SG)-like transition was noticed by increasing Mg content of the compounds. Transmission electron microscopy analysis evidenced a correlation between the magnetic transition and suppression of the monoclinic superlattice ordering with respect to the orientation of the Cd4 tetrahedron at T > 100 K. The possible origins of this phenomenon were discussed in detail. The occurrence of the AFM to SG-like magnetic transition is associated with the combination of chemical disorder due to a randomized substitution of Cd with Mg and the orientational disorder of the Cd4 tetrahedra.

Chemical speciation in Gd−Cd−M (M=Zn, Au) quasicrystal approximants

“…Interestingly, the same is the case for the tetrahedral moiety at the cluster center. When comparing with Yb(Cd 0.75 Mg 0.25 ) 6 [19] there are major differences. Mg substitution takes preferentially place at the Cd 4 tetrahedron (72 % Mg) and also in the RTH shell (position Cd5 (87 % Mg)) and the IDH shell (position Cd6 (70 % Mg)).…”

“…In particular, very recently Labib et al. reported on an extensive investigation of the phase relation between ACs and QCs in the ternary RE−Mg−Cd systems (RE=Y, Sm, Gd, Tb, Dy, Ho, Er, Tm), for which 20–25 % of Cd can be replaced by Mg, [8] and the magnetic properties of the ternary ACs and QCs [9] . Pay Gómez and Tsai studied the crystal chemical effects of Mg substitution in YbCd 6 [10] and found a pronounced preference for Mg to locate on three of the seven sites constituting the Cd substructure.…”

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

“…Such observation suggests chemical-disorder-driven AFM to spin-glass transition that presumably occurs as the Mg content of 1/1 ACs increases. A full discussion of them lies beyond the scope of the current study and will be dealt with in a separate article, which is under preparation [33].…”

On automatic determination of quasicrystal orientations by indexing of detected reflections

“…on assigning indices to the reflections. Therefore, electron backscatter diffraction (EBSD) orientation maps of quasicrystalline aggregates have been obtained by computer-aided manual indexing [1], by matching experimental patterns to simulated patterns [2] or to patterns obtained from a master reference pattern [3], and by automatic indexing using lattices of periodic approximants of quasicrystals [4]; see also [5][6][7][8][9].…”

“…on assigning indices to the reflections. Therefore, electron backscatter diffraction (EBSD) orientation maps of quasicrystalline aggregates have been obtained by computer-aided manual indexing (Tanaka et al, 2016), by matching experimental patterns to simulated patterns (Singh et al, 2019) or to patterns obtained from a master reference pattern (Winkelmann et al, 2020), and by automatic indexing using lattices of periodic approximants of quasicrystals (Cios et al, 2020); see also Baker et al (2017), Becker & Leineweber (2018), Leskovar et al (2018) and Labib et al (2019Labib et al ( , 2020.…”