Antiferromagnetic order in the quasicrystal approximant Cd6Tb studied by x-ray resonant magnetic scattering

Abstract

We have used x-ray resonant magnetic scattering at the Tb L2 edge to elucidate the nature of magnetic ordering in Cd6Tb, a 1/1 approximant closely related to the R-Mg-Cd (R = rare earth) icosahedral alloys. Below TN ≈ 24 K, the ordered moments associated with the icosahedral clusters at the corner and body-center of the pseudo-cubic unit cell are antiferromagnetically correlated and long-range magnetic order is realized.

A family of binary magnetic icosahedral quasicrystals based on rare earths and cadmium

“…icosahedral phase [3,4] and RCd 6 periodic approximants despite differences in composition. Finally, we present data that strongly suggests that the new quasicrystal phases enter into a low-temperature spin-glass (SG) state rather than manifest antiferromagnetic order as found for the RCd 6 approximants [5][6][7]. The new i-R-Cd system will play a key role as the simplest magnetic quasicrystal system, offering nonmagnetic, Y, Heisenberg-like, Gd, and non-Heisenberg (i.e.…”

Atomic structure of the i-R-Cd quasicrystals and consequences for magnetism

“…4(a) clearly displays the long-range commensurate magnetic order described previously. 26 However, even for x = 0.23 [inset to Fig. 4(b)], there is no evidence of this commensurate magnetic ordering down to the lowest temperature measured for this sample.…”

“…Binary quasicrystals provide the compositionally simplest systems for the study of magnetic interactions in aperiodic compounds. In addition, their approximant phases manifest long-range antiferromagnetic (AFM) order at low temperature, [25][26][27][28][29] offering the possibility for direct comparisons of the structural and magnetic properties among periodic and aperiodic phases.…”

Crystal electric field excitations in the quasicrystal approximantTbCd6studied by inelastic neutron scattering

“…Although TbCd 6 manifests long-range antiferromagnetic order (T N ∼ 22 K), [5][6][7] only spin-glass-like behavior is observed in i-Tb-Cd with a spin freezing temperature of T F = 6 K. 4,8 In fact, all of the known quasicrystals with local moments exhibit spin-glass-like ground states at low temperature. 9,10 The origin of the differences in magnetic behavior between the periodic approximants and quasicrystalline phases remain an open and intriguing issue, especially in light of the fact that numerous theoretical studies have established that longrange magnetic order on a quasilattice is quite possible.…”