Analysis of Ion-Irradiation Induced Lattice Expansion and Ferromagnetic State in CeO2 by Using Poisson Distribution Function

Yuki Yamamoto,Akihiro Iwase,Fuminobu Hori,Norito Ishikawa

doi:10.3390/qubs4030026

Abstract

The lattice constant and the magnetic state of CeO2 are modified by the irradiation with 200 MeV Xe ions. Under the assumption that these modifications are induced in the narrow one-dimensional region (the ion track) along the ion beam path, the dependence of the lattice constant and the saturation magnetization of CeO2 on the Xe ion fluence was analyzed by using the Poisson distribution function. The analysis reveals that the lattice constant inside the ion track, which is larger than that outside the ion track, is not affected by the overlapping of the ion track. On the other hand, the ferromagnetic state is induced inside the ion track, but the analysis shows that this ferromagnetic state is gradually destroyed due to the overlapping of the ion track. The present result implies that the Poisson distribution function is useful for describing the effect of the ion track overlapping on the ion irradiation-induced ferromagnetic state in CeO2.

Highlights

In our previous paper [1], we have reported that the ferromagnetic state is induced in CeO2 sintered pellets by the irradiation with 200 MeV Xe ions
The lattice expansion and the ferromagnetic state of CeO2 were induced by 200 MeV Xe ion irradiation
The experimental results were analyzed by using the Poisson distribution function

Summary

Introduction

In our previous paper [1], we have reported that the ferromagnetic state is induced in CeO2 sintered pellets by the irradiation with 200 MeV Xe ions. As several previous studies have already shown, the lattice defects and/or disordering contribute to the appearance of the ferromagnetism in non-magnetic oxides such as TiO2 [2], HfO2 [3], and CeO2 [4,5,6,7]. It is well-known that the high-density electronic excitation by swift heavy ions produces defective one-dimensional structures (ion-tracks) in many oxides. The result of the TEM observation suggests that the ferromagnetism of the irradiated CeO2 appears inside the ion-tracks in which the lattice structure becomes defective

Methods

Results

Conclusion