Giant magnetoresistance in CrFeMn alloys

Magnetic properties of Cr–Fe–Mn alloys

“…1(a) and 3(b), signaling an entrance into what is usually referred to in the literature [3,4,6,8,11,25] on Cr-Fe and Cr-Fe-Mn alloy systems as a ''SG-like'' [8,11] or ''spin frustration'' [7] state, on cooling through a ''SG'' freezing temperature, T f . Although the exact nature of the phase below T f is still unclear, the formation of demagnetizing FM domains that are frozen below T f and free to rotate above this temperature, can not be ruled out.…”

“…The origin of the GMR in Cr-Fe and Cr-Fe-Mn alloys was discussed by several authors [7][8][9][10]26]. There is a miscibility gap below about 800 K on the phase diagram of Cr-Fe and Cr-Fe-Mn alloys that result in a segregation of small FM Fe-rich bcc clusters, or granules, appearing in a bcc Cr/Cr-Mn-rich host matrix, when the alloy is quenched from T4800 K down to room temperature [7,16,26].…”

“…The magnetic state at low temperatures in this type of alloy system is heterogeneous for x4x c , consisting of FM regions imbedded in an AFM matrix [7,8] that results in competing FM and AFM interactions [8]. As the temperature is decreased from the PM phase there appears a PM-AFM Né el phase transition into a magnetically heterogeneous phase in which parts of the alloy transform to an AFM phase, while the rest remains in the PM phase [8].…”

“…As the temperature is decreased from the PM phase there appears a PM-AFM Né el phase transition into a magnetically heterogeneous phase in which parts of the alloy transform to an AFM phase, while the rest remains in the PM phase [8]. On further cooling, these PM regions gradually undergo a PM-FM phase transition and the system finally reaches a SG state at the lowest temperatures [8].…”

“…Due to this, there is renewed interest in the Cr 100Àx Fe x alloy system, particularly in the influence of Mn or V addition on the GMR properties at temperatures where AFM and FM domains coexist [7,8,11]. Addition of one of these two elements strengthens or weakens, respectively, the SDW AFM interactions in Cr 100Àx Fe x [2] and has a significant influence on the GMR.…”