Exchange bias effect in alloys and compounds

Abstract

Abstract. The phenomenology of exchange bias effects observed in structurally single-phase alloys and compounds but composed of a variety of coexisting magnetic phases such as ferromagnetic, antiferromagnetic, ferrimagnetic, spin-glass, clusterglass, disordered magnetic states are reviewed. The investigations on exchange bias effects are discussed in diverse types of alloys and compounds where qualitative and quantitative aspects of magnetism are focused based on macroscopic experimental tools such as magnetization and magnetoresistance measurements. Here, we focus on improvement of fundamental issues of the exchange bias effects rather than on their technological importance.

Exchange Bias Effect in La1-xAgxMnO3Nanopowders

“…The loop is pinned on vertex in the region of negative magnetization, is tilt and shifted in horizontal and vertical direction. The horizontal shift of the loop is usually expressed by exchange bias field H E = (H c+ -H c-)/2 and vertical shift is described by M E, which is defined as difference of saturated magnetization [2]; H c+ and H c-is coercive field on positive and negative axes. In the case that hysteresis loops are not very rectangular another parameter, the remnant asymmetry !…”

“…EB usually occurs in systems which are composed by an antiferromagnet (AFM) that is in atomic contact with a ferromagnet (FM) after the system is cooled, below the respective Néel and Curie temperatures T N and T C , in an external cooling field H cf . EB phenomena were observed in various materials like Laves phases, intermetallic compounds and alloys, binary alloys, Heusler alloys [2] or on layered bulk fluorometallo complex [3] where different aspects of magnetism were focused from the EB effect. The first evidence of the EB effect in mixed-valent manganites having perovskite structure was reported in a spontaneously phase separated system Pr 1/3 Ca 2/3 MnO 3 [4] which stimulated new interest for study of the EB effect in structurally single-phase compounds.…”

Magnetic Properties of La0.8K0.2MnO3Nanoparticles

“…EB usually occurs in systems which are composed by an antiferromagnet (AFM) that is in atomic contact with a ferromagnet (FM) after the system is cooled, below the respective Néel and Curie temperatures T N and T C , in an external cooling field H cf . EB phenomena were observed in various materials like Laves phases, intermetallic compounds and alloys, binary alloys, Heusler alloys [2] or on layered bulk fluorometallo complex [3] where different aspects of magnetism were focused from the EB effect. The first evidence of the EB effect in mixed-valent manganites having perovskite structure was reported in a spontaneously phase separated system Pr 1/3 Ca 2/3 MnO 3 [4] which stimulated new interest for study of the EB effect in structurally single-phase compounds.…”

Effects of coexisting spin disorder and antiferromagnetism on the magnetic behavior of nanostructured (Fe79Mn21)1−xCux alloys

“…This coupling can give rise to a shift of the magnetic hysteresis loops after field cooling, i.e., to the exchange-bias (EB) effect. 3 Among AFM systems that present exchange anisotropy when coexisting with other magnetic phases are metal transition oxide nanoparticles, [4][5][6] nanocrystalline FeRh alloy 7 and Mn-based alloys and compounds. 3,8 Within a core-shell description, mainly used to describe oxide nanoparticle systems, the surface shell behaves as a spin disordered system with spin-glass-like (SG-like) features that couples with the uncompensated AFM core giving rise to the EB phenomenon.…”

“…3 Among AFM systems that present exchange anisotropy when coexisting with other magnetic phases are metal transition oxide nanoparticles, [4][5][6] nanocrystalline FeRh alloy 7 and Mn-based alloys and compounds. 3,8 Within a core-shell description, mainly used to describe oxide nanoparticle systems, the surface shell behaves as a spin disordered system with spin-glass-like (SG-like) features that couples with the uncompensated AFM core giving rise to the EB phenomenon. [4][5][6]9 On the other side, mechanical milling applied to metallic systems produces nanostructured alloys 7 with ordered regions interconnected by disordered ones.…”