Electrical and Magnetic Properties of Quasicrystal Approximants RCd₆ (R: Rare Earth)

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

“…The sample was cooled in an orange-type cryostat and measurements were performed using a constant incident neutron wavelength of 3Å (E i = 9.3 meV), with an energy resolution of ∼ 0.4 meV determined from the width of the incoherent scattering. TbCd 6 undergoes two consecutive antiferromagnetic transitions below T N1 ∼ 22 K and T N2 ∼ 17.5 K. 5,7 All data presented here were taken in the paramagnetic phase above T N1 .…”

“…Secondly, the ground state can not be a CEF singlet, since the system orders antiferromagnetically at lower temperature. 7,33 One can also consider a negative value for B 6 and invert the CEF scheme such that the quartet Γ 4 is the ground state. In that case, the transition to the first excited state, Γ 4 → Γ 5 would be attributed to the 2.41 meV excitation and the higher transitions, Γ 5 → Γ 2 and Γ 2 → Γ 1 , are expected to be at 4.82 and 3.78 meV respectively.…”

“…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.…”

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

“…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.…”

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

“…23 Surprisingly, the 1/1 approximant to the Cd-Mg-R icosahedral phases, Cd 6 R, appears to be an exception to the rule. In particular, recent magnetic susceptibility and specific heat measurements [24][25][26] indicate the onset of long-range magnetic order at low temperature. The relatively high T N (24 K) for Cd 6 Tb, 24 in addition to the relatively strong resonant enhancement found at the Tb L-edges, 27 make it an obvious candidate for microscopic magnetic structure investigations by XRMS.…”