Magnetic properties of RCoO${}_3$ cobaltites (R = La, Pr, Nd, Sm, Eu). Effects of hydrostatic and chemical pressure

Abstract

We have investigated the temperature dependence of the magnetic susceptibility $\chi (T)$ of rare-earth cobaltites RCoO${}_3$ (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 $\chi (T)$ observed in LaCoO${}_3$ and the anomalously large pressure effect (d ln $\chi$/d$P\sim -100$ Mbar${}^{-1}$ for $T=78$ K) are analyzed in the framework of a two-level model with energy levels difference $\Delta$. The ground state of the system is assumed to be nonmagnetic with the zero spin of Co${}^{3+}$ 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 LaCoO${}_3$, indicate a significant increase in $\Delta$ with a decrease in the unit cell volume under the hydrostatic pressure. In the series of RCoO${}_3$ (R= Pr, Nd, Sm, Eu) compounds, the volume of crystal cell decreases monotonically due to a decrease in the radius of R${}^{3+}$ ions. This leads to an increase in the relative energy $\Delta$ 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 RCoO${}_3$ compounds, which we have observed at $T=300$ K.

References in corpus (14)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Structural phenomena associated with the spin-state transition in LaCoO3
• Evidence for a Low-Spin to Intermediate-Spin State Transition in LaCoO3
• Pressure-Induced Intermediate-to-Low Spin State Transition in LaCoO3
• Temperature and pressure-induced spin-state transitions in LaCoO3
• Structural anomalies associated with the electronic and spin transitions in LnCoO3
• Spin-State Transition and Metal-Insulator Transition in La${}_{1-x}$Eu${}_x$CoO${}_3$}
• The influence of the rare earth ions radii on the Low Spin to Intermediate Spin state transition in lanthanide cobaltite perovskites: LaCoO3 vs. HoCoO3
• Itinerant metamagnetism and possible spin transition in LaCoO${}_3$ by temperature/hole doping
• Structural effects on the spin-state transition in epitaxially strained LaCoO${}_3$ films
• Spin state transition and covalent bonding in LaCoO3
• Disproportionation and Metallization at Low-Spin to High-Spin Transition in Multiorbital Mott Systems
• Understanding the Thermoelectric Properties of LaCoO${}_3$ Compound
• Crystal field and magnetism of Pr${}^{3+}$ and Nd${}^{3+}$ ions in orthorhombic perovskites

Cited by in corpus (1)

• Photo-induced insulator-to-metal transition and coherent acoustic phonon propagation in LaCoO${}_3$ thin films explored by femtosecond pump-probe ellipsometry