Magnetic Compton Scattering on Sr-Doped LaCoO3

Yoshihiko Kobayashi,Yoshiharu Sakurai,Naruki Tsuji

doi:10.3390/cryst11060577

Abstract

We carried out magnetic Compton scattering experiments on the Sr-doped perovskite cobaltite La1−xSrxCoO3 for the paramagnetic insulator (x = 0.1) and the ferromagnetic metallic (x = 0.3) phases in order to investigate the electron-orbital state relevant to its unusual magnetic and electronic transport properties. The ratio of the orbital moments to the spin moments (Morbital/Mspin) is less than 1/10 at low temperatures for x = 0.3, whereas Morbital/Mspin is about 0.4 almost independent of temperature for x = 0.1. The shape of Jmag(pz) shows no apparent difference between the paramagnetic insulator and the ferromagnetic metallic phases.

Highlights

Perovskite cobaltites have been attracting the widespread interest of researchers because of their exotic physical and chemical properties, which are attributed to the multiple degrees of freedom on the spin, orbital, and lattice arising from the 3d6 electronic configuration of Co3+ [1,2,3,4]
We report magnetic Compton scattering experiments on La1− x Srx CoO3 in order to investigate the orbital-spin state of Co-3d responsible for the magnetic and electronic transport properties of Sr-doped LaCoO3 for x = 0.1 and 0.3
The calculated Compton profiles (J) of Co-3d is shown for comparison, in which the calculated J was evaluated by the sum of the J of the wave functions e g (x2 − y2 and 3z2 − r2 ) and t2g calculated using Equation (1), assuming that the contents of Co3+ and Co4+ are 0.7 and 0.3, respectively, and the LS Co4+ (e0g t52g ), intermediate spin (IS) (e1g t52g for Co3+ and e1g t42g for Co4+ ) and high spin (HS) (e2g t42g for Co3+ and e2g t32g for Co4+ ) exist without weight

Summary

Introduction

Perovskite cobaltites have been attracting the widespread interest of researchers because of their exotic physical and chemical properties, which are attributed to the multiple degrees of freedom on the spin, orbital, and lattice arising from the 3d6 electronic configuration of Co3+ [1,2,3,4]. One of the examples is the unusual spin-crossover phenomena of. The magnetic anomaly at around 500 K is accompanied by an insulator-to-metal transition (IMT). These phenomena are considered to be the temperature-induced spin-crossover from the nonmagnetic low-spin (LS; (t2g ↑) (t2g ↓) , S = 0) ground state to magnetic excited states (↑ and ↓ denote up and down spins, respectively) [6]. Despite the decades of research history and the extensive efforts of researchers, there is still controversy regarding whether the magnetic excited state induced around 100 K is intermediate spin (IS; (t2g ↑) (e g ↑) (t2g ↓)2 ,. Neither spin-state model can comprehensively explain all the important experimental findings [6,7,8,9,10,11]

Results

Discussion

Conclusion