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Berlin 2018 – scientific programme

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MA: Fachverband Magnetismus

MA 21: Poster I

MA 21.68: Poster

Tuesday, March 13, 2018, 09:30–13:00, Poster A

Large uniaxial magnetostriction with sign inversion at the first order phase transition in Mn2GaC filmsIuliia Novoselova1, •Ruslan Salikhov1, Andrejs Petruhins2, Arni Ingason2, Johanna Rosen2, Ulf Wiedwald1, and Michael Farle1,31Faculty of Physics and CENIDE, University of Duisburg-Essen, Germany — 2Department of Physics, Linköping University, Linköping, Sweden — 3Center for Functionalized Magnetic Materials, Immanuel Kant Baltic Federal University, Kaliningrad, Russia

Mn+1AXn (n = 1,2,3) phases are a family of inherently nanolaminated hexagonal compounds. The new Mn2GaC MAX phase was synthesized as hetero-epitaxial films containing Mn as the exclusive M-element [1]. Here, we present a comprehensive study of magnetic phase transitions in the Mn2GaC films. The Néel temperature is TN ∼ 507 K, at Tt = 214 K the material undergoes a first order phase transition from antiferromagnetic (AFM) above Tt to a non-collinear AFM spin structure. Both states show large uniaxial c-axis magnetostriction of 450 ppm. Remarkably, the magnetostriction changes sign, being compressive (negative) above Tt and tensile (positive) below the Tt. The sign change of magnetostriction coefficient across the phase transition is a consequence of the layered structure and competing AFM and FM exchange interactions between magnetic atomic layers. The sign change of the magnetostriction is accompanied by a sign change in the magnetoresistance indicating a coupling between the spin, lattice and electrical transport properties. The work is supported by DFG Grant SA 3095/2-1. [1] Dahlqvist, M. et al. Phys. Rev. B 93, 014410 (2016).

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