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Article Dans Une Revue Physical Review Materials Année : 2021

Magnetic-field-induced structural phase transition and giant magnetoresistance in La0.85Ce0.15Fe12B6

Résumé

Magnetoelastic coupling, structural, magnetic, electronic transport, and magnetotransport properties of La0.85Ce0.15Fe12B6 have been studied by a combination of macroscopic [magnetization, electrical resistivity, and magnetoresistance (MR)] and microscopic temperature-and magnetic-field-dependent x-ray powder diffraction measurements. The itinerant-electron system La0.85Ce0.15Fe12B6 exhibits an antiferromagnetic (AFM) ground state and multiple magnetic transitions, AFM-ferromagnetic (FM) and FM-paramagnetic (PM), triggered by changes in both temperature and magnetic fields. At low temperatures, the field-induced first-order AFM-FM metamagnetic phase transition is discontinuous, manifesting itself by extremely sharp steps in magnetization as well as in MR and is accompanied by large magnetic hysteresis. A remarkably large negative MR of −73% was discovered. In addition, the time evolution of the electrical resistivity displays a colossal spontaneous jump when both the applied magnetic field and temperature are constant. Diffraction data reveal a magnetic-field-induced structural phase transition associated with the AFM-FM and PM-FM transformations. The lattice distortion is driven by magnetoelastic coupling and converts the crystal structure from rhombohedral (R-3m) to monoclinic (C2/m). The AFM and PM states are related to the rhombohedral structure, whereas the FM order develops in the monoclinic symmetry. A huge volume magnetostriction of ∼0.9% accompanies this symmetry-lowering lattice distortion. Meanwhile, a highly anisotropic thermal expansion involving giant negative thermal expansion with an average volumetric thermal expansion coefficient αV = −195×10−6 K−1 was observed. The consistency seen in these different experimental data constitutes direct evidence of the strong correlations between charge, magnetic, and crystallographic degrees of freedom in this material.
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Dates et versions

hal-03380209 , version 1 (15-10-2021)

Identifiants

Citer

L. V. B. Diop, T. Faske, O. Isnard, W. Donner. Magnetic-field-induced structural phase transition and giant magnetoresistance in La0.85Ce0.15Fe12B6. Physical Review Materials, 2021, 5 (10), pp.104401. ⟨10.1103/PhysRevMaterials.5.104401⟩. ⟨hal-03380209⟩
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