Experimental study on the response of phason strains of the quasicrystals

点击翻译按钮获取中文摘要

The dependence of the magnetic susceptibility on time was investigated in F-type Al-Pd-Mn icosahedral alloys after the change in the temperature. The susceptibility varied as a square root of time, which is characteristic of the relaxation of the phason in the theory of the strain response of the quasicrystal. Such a change in the susceptibility was considered to originate from the critical conditions for the formation of local magnetic moments in the Al-Pd-Mn icosahedral alloys, which resulted in the fact that only a small fraction of the whole Mn atoms had magnetic moment. These facts leaded to the investigations of the atomic positions in the Al-Pd-Mn icosahedral phases and related crystal approximants. Atomic clusters and the positions of Mn atoms were determined in the investigations, and a new structure related to the phason strains was found. The study of the time-dependence of the macroscopic strain is under way on applying stress.Simulation calculations were performed for the magnetic structures in a model of atomic positions of Ho in F-type Zn-Mg-Ho icosahedral phase at low temperatures on the assumption that the Ho atoms were interacting via RKKY-like alternating interactions. A long-range antiferromagnetic order was found in the case of the antiferromagnetic interaction for the shortest Ho-Ho distance and the ferromagnetic one for the second shortest Ho-Ho distance. Only a short-range antiferromagnetic order was found in the case of the reversed sign interactions. These facts strongly suggest that the phason strains affect the magnetism of the icosahedral phases drastically.