Theory of Singlet-Ground-State Ferromagnetism in Pr₃Se₄: A Cubic System with Low Local Symmetry

Abstract

The magnetic properties of^1–5 Pr₃Se₄ have two very interesting features related to crystal-field and structural effects. One of these comes from the fact that despite the overall cubic symmetry, the local Pr symmetry is quite low. On considering a crystal field interaction, this leads to some remarkable anisotropic effects in the theoretically expected magnetic ordering and magnetization in applied field. The second striking aspect of the magnetic behavior of Pr₃Se₄ is the marked reduction of the magnetization for low applied pressure.^4,5 The spontaneous magnetization decreases by about 50% for a pressure of only 0.5 kbar. In this paper we shall concentrate on the first aspect, the peculiarities of behavior expected on the basis of low crystal-field symmetry within a context of overall cubic symmetry. We shall relate this to the experimental behavior,^4,5 and also briefly remark on the fact that the extraordinary sensitivity may be related to the inability to obtain quantitative compatibility with the overall experimental magnetic behavior on the basis of a simple model for the crystal-field and exchange interactions.

Supported by National Science Foundation Grant No. 79-07069

Supported by National Science Foundation Grant No. 79-18066, Visiting Scientist at the Francis Bitter National Magnet Laboratory.

Supported by the National Science Foundation.