Itinerant Magnetism in Ga-Rich Ga–Mn–Co Full Heusler Alloys

Abstract

Herein, the crystal structure and the magnetic and electrical properties of two Ga-rich, off-stoichiometric full Heusler-type compositions (Formula presented.) with x = 0.2 and 0.4 are investigated. The innate site disorder in the crystal structure is clarified using synchrotron X-ray diffraction (XRD) studies. Experimentally, it is observed that a control over magnetic ordering temperature ((Formula presented.)) and total magnetic moment can be achieved by tuning the Ga:Mn ratio in these alloys. Consequently, for the resultant compositions, (Formula presented.) and (Formula presented.), Curie temperatures of ≈245 and 375 K, respectively, are obtained, lying in the vicinity of room temperature. The atomic site disorder arising out of excess Mn leads to spin fluctuation scattering which is reflected in its magnetic and transport properties. Temperature dependence of resistivity shows an anomalous occurrence of a maximum, reflecting a change in the sign of the temperature coefficient of resistance, coincidental with (Formula presented.). Furthermore, the magnetization results indicate an itinerant-type ferromagnetic ground state over the Heisenberg-type state, with the moment values as low as 0.35 (Formula presented.). © 2020 Wiley-VCH GmbH