Giant magnetoresistance inCe2Fe17

Abstract

Using a single-phase sample of Ce 2 Fe 17 with the rhombohedral Th 2 Zn 17-type structure, we measured the magnetization, resistivity, and specific heat under various magnetic fields up to 5.5 T. Below T c ϭ125 K, giant magnetoresistance ͑GMR͒ is induced by the metamagnetic transition from the antiferromagnetic to ferromagnetic states. The value of ⌬/(Х AF Ϫ F)/ AF) reaches 0.85 at 4.2 K, while the value ␥ (ХC/T at 0 K͒ of 351 mJ/K 2 /mole in zero field only decreases ϳ20% by the metamagnetic transition. These results suggest that GMR is due to the closing of a superzone gap formed by antiferromagnetic ordering of Fe spins, while the large ␥ value is due to valence fluctuations of the Ce-4 f electrons, weakly dependent on magnetic field.

Magnetic phase diagrams of Ce2Fe17−xMnx–H system: A magnetization study

“…Previous neutron diffraction studies [1] have shown that Ce 2 Fe 17 compound undergoes successive magnetic phase transitions, accompanied by changes of the ordering mode which is from paramagnetic state to helicoidal antiferromagnetic and finally to the ferromagnetic spin structure at low temperatures. The thermal variation of the magnetization under a field of 100 Oe for Ce 2 Fe 17 is peculiar [3]. A magnetization peak characteristic of a Néel temperature is observed at T N = 206 K. Another anomaly at T T = 94 K where magnetization strongly increases corresponds to the spontaneous magnetization characteristic for ferromagnetic ordering.…”

“…2, the selected typical isofield magnetization curves are presented for Ce 2 Fe 15.7 Mn 1. 3 and Ce 2 Fe 15.7 Mn 1.3 H 1.0 . From these typical traces the thermal dependence of H C the critical field transitions between ferromagnetic, helical, and paramagnetic states were established.…”

Magnetoelasticity of (Lu0.8Ce0.2)2Fe17 intermetallic compound

“…7). All these features point to a possible phase transition similar to the one observed in Ce 2 Fe 17 at 124 K [7,9] between two AF phases (the transition temperature is given as 118 K in ref. [18]).…”

“…Ce 2 Fe 17 crystallizes non-congruently and the magnetic properties are very sample-dependent. Two types of magnetic structures in the ground state for Ce 2 Fe 17 have been observed, F ( [1,4,5]) and AF as a modified helical spin structure without any ferromagnetic component [6][7][8][9]. In the refs.…”

Magnetic properties and magneto-caloric effect in pseudo-binary intermetallic (Ce,R)2Fe17 compounds (R = Y, Pr and Dy)

“…Ce 2 Fe 17 can yield to a complex magnetic phase diagram, since antiferromagnetic, ferromagnetic noncollinear and helimagnetic magnetic structures are possible [12,16,17]. Moreover, a metamagnetic transition from a modified helix structure to a ferromagnetic one or between helimagnetic phases can be caused either by an external magnetic field or under high pressures [18]. Apart from that, the magnetic state of Ce 2 Fe 17 is unstable and sample dependent at low temperatures, even though in this compound Cerium has no magnetic moment because of its Ce 3þ ÀCe 4þ intermediate valence state [19,20].…”