Pressure study of the magnetic and electrical properties of the Eu-Yb alloy system

Kadomatsu Hideoki

Tsutaoka Takanori

Fujiwara Hiroshi

Physical Review B

Measurements of the ac magnetic susceptibility, magnetization, and electrical resistivity at hydrostatic pressures up to 15 kbar and of the thermal expansion were made for the EuxYb1-x alloy system (x≤0.4) in temperatures from 1.6 to 400 K. The paramagnetic-ferromagnetic transition temperature Tc versus pressure p curve for x=0.025 has a maximum near p=1 kbar. For x=0.25, Tc decreases and the ferromagnetic–spin-glass-like transition temperature Tt increases at rates of ΔTc/Δp=-9.5 K/kbar and ΔTt/Δp=+1.7 K/kbar, respectively. The ferromagnetic region disappears near p=2.5 kbar, and above it the paramagnetic–spin-glass-like transition temperature Tg, which is pressure insensitive, appears. The Tg value for x=0.35 decreases initially and increases slowly with increasing p above p=2 kbar at a rate of ΔTg/Δp=+0.15 K/kbar. Both the magnetization in the ferromagnetic concentration range and the value of the ac magnetic susceptibility near Tg in the spin-glass-like state decrease with increasing p. From electrical-resistivity measurements under various pressures, semiconducting character was observed at the ambient pressure for x=0.35 and the transition from semimetallic to semiconducting states appears with increasing p for x=0.025. Thermal expansion shows the large positive volume magnetostriction. These results of the measurements under pressure are discussed on the basis of the Ruderman-Kittel-Kasuya-Yosida interaction by considering that the dominant variable is the number of carriers (electrons or holes) which is strongly controlled by the pressure.

eng

American Physical Society

Copyright (c) 1985 The American Physical Society.

[ISSN] 0163-1829

[DOI] 10.1103/PhysRevB.32.7483

[NCID] AA00362255

[DOI] http://dx.doi.org/10.1103/PhysRevB.32.7483