Probing the bulk valence of Sm in SmB6 by studying the magnetic susceptibility under pressure

• Published in: Low temperature physics (Woodbury, N.Y.) N.Y.), 2023-09, Vol.49 (9), p.1037-1042
• Main Authors: Panfilov, A. S., Desnenko, V. A., Lyogenkaya, A. A., Grechnev, G. E., Shitsevalova, N. Yu
• Format: Article
• Language: English
• Subjects: Conduction bands; Electronic structure; Gas pressure; Helium; Initial pressure; Magnetic permeability; Paramagnetism; Pressure dependence; Pressure effects; Temperature dependence
• ISSN: 1063-777X; 1090-6517
• DOI: 10.1063/10.0020596

For one of the most famous and widely investigated intermediate-valence compound SmB6, we report the results of a precise experimental study of the pressure effect on magnetic susceptibility χ. The measurements of χ(P) were carried out under helium gas pressure P up to 2 kbar at fixed temperatures 78 and 300 K using a pendulum-type magnetometer. The observed pressure effect value, d lnχ/dP ∼ –6 Mbar–1, demonstrates a noticeable decrease in susceptibility under pressure, which is weakly dependent on temperature used. From model analysis of the experimental data, combined with the supplemented LSDA + U calculations of the electronic structure and van Vleck paramagnetism of the band states of SmB6, we have estimated the value of the initial pressure derivative for the intermediate valence of Sm. It is consistent with the literature data obtained by other methods and indicates an increase in valence with increasing pressure. It was shown that the valence of Sm and its pressure dependence are closely related to the detailed characteristics of the conduction band and 4f states.