Magnetic anisotropy and relaxation in a new class of inherently nanolaminated magnetic materials: magnetic MAX phases

• Applicant: Dr. Ruslan Salikhov
• Subject Area: Experimental Condensed Matter Physics ; Synthesis and Properties of Functional Materials
• Term: from 2016 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 319409675

Recently discovered inherently nanolaminated magnetic materials, magnetic MAX phases, show plethora unique properties, which offer intriguing perspectives for use in spintronics, magnetoelectric, magnetic storage or magnetic sensor applications. MAX phases (Mn+1AXn, where n = 1, 2, or 3) are composed of an early transition metal M (including Mn), an A-group element A, and either C or N, denoted X. The crystal structure of MAX phases is hexagonal with repeated M-X-M (quasi 2D) atomic layers stacking in the c direction with A-element spacer. This class of materials shows combined properties associated with metals (electrically and thermally conductive, high bulk modulus and damage tolerant) and ceramics (lightweight, stiff and resistive against oxidation). The spin structure of magnetic MAX phases and their magnetic properties are still to be investigated. First principle calculations predict strong ferromagnetic coupling of magnetic moments within the basal (M-X-M) plane. These ferromagnetic M-X-M layers then are weakly ferromagnetically and/or antiferromagnetically coupled in the c direction. Calculations also suggest strongly anisotropic electrical conductivity with much higher value within the basal plane as compared to the one along the c axis. Coupling of magnetic properties with structural or electrical transport properties in these anisotropic systems may result in new physical phenomena which, in turn, can bring new functionalities. The spin-orbit interaction is one of the fundamental principles of coupling between magnetic spin and the crystal lattice (magnetostriction) or the electrical conductivity. We systematically study the magnetic properties of epitaxial (CrMn)2GeC, (CrMn)2GaC, (MoMn)2GaC, (VMn)2GaC and Mn2GaC films with the c-axis perpendicular to the film surface. The main focus of our study is set to the spin-orbit related characteristics such as magnetocrystalline anisotropy, spectroscopic splitting (g-) factor and magnetic relaxation rate (damping). These parameters will be determined using ferromagnetic resonance (FMR) and will be correlated with the results of structural, magnetometry and electrical transport measurements. The study will be performed for samples with variable Mn content and with different thicknesses in order to understand the effect of Mn doping and influence of surface (interface) on the studied properties, accordingly. Our study will significantly contribute to the understanding of magnetic properties of the recently discovered magnetic MAX phases in general and will provide the key information on spin-orbit related phenomena, what is important for judging the potential for applications e. g. spintronics, magnetic memory or magnetic sensors.

• DFG Programme: Research Grants
• International Connection: Sweden
• Co-Investigators: Professor Dr. Michael Farle; Professor Dr. Ulf Wiedwald
• Cooperation Partner: Professorin Dr. Johanna Rosen