Investigation of the spin glass transition in a low U doped YRu₂Si₂sample

Abstract

We have made extensive studies of a dilute U doped YRu2Si2 alloy using several experimental techniques such as ac and dc magnetic susceptibility, dc resistivity and microstructural investigations. The real part of the ac susceptibility shows a maximum at around 6.75 K for f = 7 Hz. With increasing frequency, the temperature of this maximum increases while, at the same time, the magnitude of the maximum decreases, which is a typical spin glass behaviour. The magnitude of the imaginary part shows frequency-dependent behaviour too. We show that most of the imaginary part of the susceptibility, at least over the range of the frequencies we used, comes from the conduction electrons. Zero-field cooling and field cooling dc magnetization measurements also indicate the presence of a spin glass transition at about the same temperature. We also found that relaxation processes below the freezing temperature show ln(t + tO) behaviour. We discuss our findings in light of the origin of the spin glass behaviour and compare them with other similar studies.

Spin-glass-like behaviour in the ternary U3Fe4+xAl12−x uranium–iron aluminide

“…This last equation implies a linear dependence of T f with 1/ln(u 0 /u) and has been often used to describe the slowing down of the relaxation found in spin glasses [19], with T 0 having the same order of magnitude of T f . The Vogel-Fulcher plot for U 3 Fe 4þx Al 12Àx is shown in Fig.…”

Structural and electronic properties of the highly concentrated UxY1−xRu2Si2 alloy system

“…The existence of two crystalline phases even in such low concentrated alloy was revealed. It was shown that only c = 0.035 of U was in the solid solution in this investigated sample [12].…”

“…Under a reasonable assumption that the density of electronic states g does not vary significantly for the above mentioned compounds, we conclude that hybridization in the U x Y 1−x Ru 2 Si 2 alloys is weak. This could explain why Kondo interaction is not observed for the lower concentrations of U [8][9][10][11][12][13]. In addition, the influence of the secondary phase, which exists also even for the lowest concentrations investigated [12] on the transport properties, is probably more significant for the low U concentrations.…”

“…However, neither of these alloy systems shows a resistivity upturn at low temperatures, a hallmark of the Kondo interaction on the lowest doublet of a CEF levels, although one takes the U ion is a Kondo ion, like Ce or Yb are. Because of the absence of the sign of the one-channel Kondo scattering, the low temperature anomalous features were explained within multi-channel Kondo scattering, quadrupolar interactions [8,9] or by intersite interactions, which eventually lead to spin glass behaviour [10][11][12][13]. A clear spin-glasslike behaviour for a sample with nominally x = 0.08 concentration of U was found in U x Y 1−x Ru 2 Si 2 .…”

Transport properties of the CexLa1−xPt alloy system

“…Further point pertaining to the presented work here is the fact that the spin glass GS can be formed with very small concentration of a Kondo ion in some metal matrix. For example, only less than 0.1 at.% of U forms the spin glass GS in Yru 2 Si 2 [10,11]. This spin glass shows ferromagnetic like behavior.…”