Electric field controlled magnetic exchange bias and magnetic state switching at room temperature in Ga-doped α-Fe2O3 oxide

Abstract

We have developed a new magnetoelectric material based on Ga doped α-Fe2O3 in rhombohedral phase. The material is a canted ferromagnet at room temperature and showing magneto-electric properties. The experimental results of electric field controlled magnetic state provided a direct evidence of room temperature magnetoelectric coupling in Ga doped α-Fe2O3 system. Interestingly, (un-doped) α-Fe2O3 system does not exhibit any electric field controlled magnetic exchange bias shift, but Ga doped α-Fe2O3 system has shown an extremely high electric field induced magnetic exchange bias shift up to the value of 1120 Oe (positive). On the other hand, in a first time, we report the electric field controlled magnetic state switching both in α-Fe2O3 and in Ga doped α-Fe2O3 systems. The switching of magnetic state is highly sensitive to ON and OFF modes, as well as to the change of polarity of applied electric voltage during in-field magnetic relaxation experiments. The switching of magnetic state to upper level for positive electric field and to down level for negative electric field indicates that electric and magnetic orders are coupled in the Ga doped hematite system. Such material is of increasing demand in today for multifunctional applications in next generation magnetic sensor, switching, non-volatile memory and spintronic devices. Keywords: Ga doped hematite, Rhombehedral structure, Exchange bias, Room temperature magneto-electrics, Electric field controlled magnetic state. Recently, some hetero-structured materials, either naturally exist (β-NaFeO2 [12]) or designed superlattices ((LuFeO3)9/(LuFe2O4)1 [13], Ti0.8Co0.2O2/Ca2Nb3O10/Ti0.8Co0.2O2 [14]) or theoretically predicted (R2NiMnO6/La2NiMnO6 [15]) exhibited electric field controlled

Structure, Defects, and Magnetism of Electrospun Hematite Nanofibers Silica-Coated by Atomic Layer Deposition

“…In the latest years, by virtue of its appealing properties (ubiquity, high abundance, low-cost, environmental friendliness, nontoxicity, good chemical stability, small energy band gap), hematite (α-Fe 2 O 3 ) has gained a position of relevance in the scenery of materials suitable for sustainable applications. It is utilized in a wide variety of fields transversally involving biomedics, − environmental remediation, − magnetic data-storage and spintronics, − sensing, − and energy conversion and storage. − …”

Existence of two spin dynamics in the temperature and magnetic field dependence of the magnetization curves of ferrimagnetic Co1.75Fe1.25O4 and its composite with BaTiO3

“…, where is the gyromagnetic ratio and is the Gilbert damping factor [32]. The equation can be re-written as , where = [33].…”

Structural phase stabilization via Ba site doping with bivalent Sr, Ca and Zn ions and Fe site doping with trivalent Cr and Ga ions in the BaFe12O19 hexaferrite and its magnetic modification

“…25 The additional heat treatment of the mechanically alloyed samples at higher temperatures improves the chemical homogeneity and magnetic properties, making them either comparable or better than those obtained by employing chemical routes. [26][27][28][29] The element-specific doping effects either at Ba or Fe sites of the BaM structure have been studied in the literature. A comparative study of the magnetic properties by doping both at Ba sites and Fe sites is very much missing from the literature.…”

“…25 The additional heat treatment of the mechanically alloyed samples at higher temperatures improves the chemical homogeneity and magnetic properties, making them either comparable or better than those obtained by employing chemical routes. 26–29…”