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Conduction electrons in aperiodic versus periodic structures: An ESR study of quasicrystalline i-Y(Gd)-Cd and its approximant Y(Gd)Cd-6

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Author(s):
Cabrera-Baez, M. ; Avila, M. A. ; Rettori, C.
Total Authors: 3
Document type: Journal article
Source: PHYSICAL REVIEW B; v. 100, n. 1, p. 7-pg., 2019-07-31.
Abstract

A formal description of collective electronic states in condensed-matter systems lacking long-range periodicity remains a theoretical challenge. To experimentally explore the differences in electronic and magnetic behavior between metallic quasicrystals (QCs) and their conventional crystalline analogs [quasicrystal approximants (QCAs)], we have grown single crystals of Y1-xGdx-Cd6 (QCA) together with their QC counterparts i-Y1-xGdx-Cd for x = 0.006, 0.01, 0.1, and 1.00, and we carried out comparative T-dependent electron spin resonance (ESR) measurements. On the high Gd concentration side, x = 1.00, we confirm that GdCd6 adopts an antiferromagnetic ground state below T-N similar to 22 K, whereas i-Gd-Cd presents spin-glass-like behavior showing similar local and dynamical properties from the point of view of ESR. For the diluted samples, our ESR experimental results show similar local conduction electron polarization behavior at the Gd3+ site in all QC/QCA pairs investigated, supporting the validity of using QCAs as periodic representations of QCs in terms of short-range electronic interactions. However, there is a measurable difference in the Korringa relaxation rate (spin-flip relaxation process between the localized Gd3+ 4f electron and the delocalized s-type conduction electrons at the Fermi surface) between the QC/QCA pairs probably associated with the lack of periodicity. We expect that our comparative ESR study may provide support and motivation for the development of new theoretical approaches toward a generalized band-structure theory, contemplating condensed-matter systems beyond the scope of traditional periodicity. (AU)

FAPESP's process: 16/15780-0 - Study of the physical properties of nanostructured materials and fundamental interactions in bulk systems
Grantee:Michael Cabrera Baez
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 11/19924-2 - Study and development of advanced novel materials: electronic, magnetic and nanostructured: an interdisciplinary approach
Grantee:Carlos Rettori
Support Opportunities: Research Projects - Thematic Grants