Magnetovolume effect in Ce(Ni{1-x}Cu{x})5 alloys

TL;DR

This study investigates how hydrostatic pressure affects the magnetic susceptibility of Ce(Ni{1-x}Cu{x})5 alloys, revealing a strong, non-monotonous dependence linked to Ce valence changes and providing ab initio calculations for CeNi5.

Contribution

It provides new experimental data on pressure effects across different Cu contents and offers ab initio calculations that align with experimental findings, enhancing understanding of valence instability.

Findings

Pressure effect on susceptibility is negative and varies with Cu content.

Maximum pressure sensitivity occurs near x=0.4.

Ab initio calculations agree with experimental data for CeNi5.

Abstract

Magnetic susceptibility of the isostructural Ce(Ni{1-x}Cu{x})5 alloys (0< x <0.9) was studied as a function of the hydrostatic pressure up to 2 kbar at fixed temperatures 77.3 and 300 K, using a pendulum-type magnetometer. A pronounced magnitude of the pressure effect is found to be negative in sign and to depend strongly and non-monotonously on the Cu content, showing a sharp maximum in vicinity of x = 0.4. The experimental results are discussed in terms of the Ce valence change under pressure. It has been concluded that the fractional occupation of the f-states, which corresponds to the half-integer valence of Ce ion (3.5), is favorable for the valence instability in alloys studied. For the reference CeNi5 compound the main contributions to magnetic susceptibility and their volume dependence are calculated ab initio within the local spin density approximation (LSDA), and appeared to be in close agreement with experimental data.