Ferrites – what is new?

Pramana

R Ranganathan1¹  Anindita Ray¹ 

[1] Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, l/AF, Bidhannagar, Calcutta 700 064, India$$

关键词: Ferrites;    conductivity;    magnetoresistance;    spin compensation temperature;    irradiation effect;    nanoparticle.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

Ferrites, combining insulating and ferrimagnetic properties, have long been used in technology. The aim of this paper is to focus on new features in these materials. In the classical theory of ferrimagnets, Neel had predicted the unusual thermal variation of the spontaneous magnetization, such as, the disappearance of the magnetization at a temperature which was not the Curie temperature but at a point where there was compensation of the spontaneous magnetization of the two sublattices. We show experimentally that temperature (𝑇K) in spinel oxide is different under the ZFC and FC magnetization method. To our knowledge, only limited attempt has been made to study 𝑇K as very few systems exhibit such behavior. In general, some of the ferrites have specific semiconducting properties, e.g., a very low carrier mobility. We discuss the anomalies of the magneto-resistance in ferrites that occur at order–disorder and order–order magnetic phase transition along with our ac and dc conductivity data near the spin compensation temperature. Another notable feature of the ferrites is that, upon irradiation of heavy ions, one can tune the magnetic ordering on bulk sample without destructive effects, i.e., irradiation-induced magnetization. It is interesting to note that spinel ferrite (nano) particle is an ideal small particle magnetic system as the crystal chemistry issue can be controlled, unlike pure metal particle systems where the crystal chemistry issues are basically fixed. In relevance to this, we will also discuss the future prospects, namely, the effect of irradiation on small particle magnetism, as, so far, only a limited attempt has been made in this field.

【 授权许可】

Unknown