title: Possible magnetic-polaron-switched positive and negative magnetoresistance in the GdSi single crystals.
abstract: Magnetoresistance (MR) has attracted tremendous attention for possible technological applications. Understanding the role of magnetism in manipulating MR may in turn steer the searching for new applicable MR materials. Here we show that antiferromagnetic (AFM) GdSi metal displays an anisotropic positive MR value (PMRV), up to ~415%, accompanied by a large negative thermal volume expansion (NTVE). Around T(N) the PMRV translates to negative, down to ~-10.5%. Their theory-breaking magnetic-field dependencies [PMRV: dominantly linear; negative MR value (NMRV): quadratic] and the unusual NTVE indicate that PMRV is induced by the formation of magnetic polarons in 5d bands, whereas NMRV is possibly due to abated electron-spin scattering resulting from magnetic-field-aligned local 4f spins. Our results may open up a new avenue of searching for giant MR materials by suppressing the AFM transition temperature, opposite the case in manganites, and provide a promising approach to novel magnetic and electric devices.
authors.affiliation: Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at Institut Laue-Langevin, Boîte Postale 156, F-38042 Grenoble Cedex 9, France. h.li@fz-juelich.de
authors.forename: Haifeng
authors.initials: H
authors.lastname: Li
authors.forename: Yinguo
authors.initials: Y
authors.lastname: Xiao
authors.forename: Berthold
authors.initials: B
authors.lastname: Schmitz
authors.forename: Jörg
authors.initials: J
authors.lastname: Persson
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schmidt
authors.forename: Paul
authors.initials: P
authors.lastname: Meuffels
authors.forename: Georg
authors.initials: G
authors.lastname: Roth
authors.forename: Thomas
authors.initials: T
authors.lastname: Brückel