Magnetic properties of RCoO3 cobaltites (R = La, Pr, Nd, Sm, Eu). Effects of hydrostatic and chemical pressure

A. S. Panfilov, G. E. Grechnev, A. A. Lyogenkaya, V. A. Pashchenko, I. P. Zhuravleva, L. O. Vasylechko, V. M. Hreb, V. A. Turchenko, D. Novoselov

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15 Citations (Scopus)

Abstract

We have investigated the temperature dependence of the magnetic susceptibility χ(T) of rare-earth cobaltites RCoO3 (R = La, Pr, Nd, Sm, Eu) in the temperature range 4.2–300 K and also the influence of hydrostatic pressure up to 2 kbar on their susceptibility at fixed temperatures T = 78 and 300 K. The specific dependence χ(T) observed in LaCoO3 and the anomalously large pressure effect (dln χ/dP ∼−100 Mbar 1 for T = 78 K) are analyzed in the framework of a two-level model with energy levels difference Δ. The ground state of the system is assumed to be nonmagnetic with the zero spin of Co3+ ions, and magnetism at a finite temperature is determined by the excited magnetic spin state. The results of the analysis, supplemented by theoretical calculations of the electronic structure of LaCoO3, indicate a significant increase in Δ with a decrease in the unit cell volume under the hydrostatic pressure. In the series of RCoO3 (R = Pr, Nd, Sm, Eu) compounds, the volume of crystal cell decreases monotonically due to a decrease in the radius of R3 + ions. This leads to an increase in the relative energy Δ of the excited state (the chemical pressure effect), which manifests itself in a decrease in the contribution of cobalt ions to the magnetic susceptibility at a fixed temperature, and also in a decrease in the hydrostatic pressure effect on the susceptibility of RCoO3 compounds, which we have observed at T = 300 K.

Original languageEnglish
Pages (from-to)80-87
Number of pages8
JournalPhysica B: Condensed Matter
Volume553
DOIs
Publication statusPublished - 15 Jan 2019
Externally publishedYes

Keywords

  • Electronic band structure
  • High-pressure
  • Magnetic measurements
  • Magneto-volume effects
  • Rare earth alloys and compounds

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