Tuning the electronic hybridization in the heavy fermion cage compound YbFe2Zn20 with Cd doping

Author(s)

Cabrera-Baez, M. ; Ribeiro, R. A. ; Avila, M. A.

• Document type: Journal article
• Source: JOURNAL OF PHYSICS-CONDENSED MATTER; v. 28, n. 37 SEP 21 2016.
• Web of Science Citations: 4

Abstract

The tuning of the electronic properties of heavy fermion compounds by chemical substitution provides excellent opportunities for further understanding the physics of hybridized ions in crystal lattices. Here we present an investigation on the effects of Cd doping in flux-grown single crystals of the complex intermetallic cage compound YbFe2Zn20, which has been described as a heavy fermion with a Sommerfeld coefficient of 535 mJ mol(-1) . K-2. The substitution of Cd for Zn disturbs the system by expanding the unit cell and, in this case, the size of the Zn cages that surround the Yb and Fe. With an increasing amount of Cd, the hybridization between the Yb 4f electrons and the conduction electrons is weakened, as shown by a decrease in the Sommerfeld coefficient, which should be accompanied by a valence shift of the Yb3+ due to the negative chemical pressure effect. This scenario is also supported by the low temperature DC magnetic susceptibility, which is gradually suppressed and shows an increment of the Kondo temperature, based on a shift to higher temperatures of the characteristic broad susceptibility peak. Furthermore, the DC resistivity decreases with the isoelectronic substitution of Cd for Zn, contrary to expectations in an increasingly disordered system, and implying that the valence shift is not related to charge carrier doping. The combined results demonstrate the excellent complementarity between positive physical pressure and negative chemical pressure, and point to a rich playground for exploring the physics and chemistry of strongly correlated electron systems in the general family of Zn-20 compounds, despite their structural complexity. (AU)

• FAPESP's process: 12/17562-9 - Preparation of oriented single crystals for studies on electronic, magnetic and thermal anisotropies
• Grantee: Marcos de Abreu Avila
• Support Opportunities: Regular Research Grants
• 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