FIRST DIRECT EVIDENCE OF LONG RANGE MAGNETIC ORDERING IN BULK MAX PHASE

El'ad Nisan Caspi ^1,2 Oleg Rivin ^1,3 Asaf Pesach ¹ Hagai Shaked ⁴ Andreas Hoser ⁵ Robert Georgii ⁶ Quanzheng Tao ⁷ Johanna Rosen ⁷ Michel Barsoum ²

¹Physics, Nuclear Research Center Negev, Beer-Sheva, Israel
²Materials Science and Engineering, Drexel University, Philadelphia, PA, USA
³High Field Magnet, Helmholtz-Zentrum Berlin für Materialen und Energie, Berlin, Germany
⁴Physics Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel
⁵Structure and Dynamics of Energy Materials, Helmholtz-Zentrum Berlin für Materialen und Energie, Berlin, Germany
⁶Forschungsneutronenquelle Heinz Maier-Leibnitz, Technische Universität München, Garching, Germany
⁷Physics, Chemistry and Biology Department, Linköping University, Linköping, Sweden

The M_n+1AX_n (MAX) phases are a large family of hexagonal nano-laminated ternary carbides, and nitrides with M an early transition metal, A a group A element, X carbon and/or nitrogen, and n=1, 2, or 3. Interest in these ceramics have increased significantly in recent years due to their vast applicative potential. One of the most sought for attributes is spontaneous long-range magnetism. Moreover, since MXenes are the 2D derivatives of MAX phases, a magnetic MAX could be the precursor for long range ordered 2D magnetic material. Many theoretical work has been done in the last few years predicting long range magnetic MAX phases in several compounds. However, experimental proof for bulk magnetism in such materials is limited to observations of macroscopic response and no understanding could be drawn from these measurements on the microscopic magnetic behavior of individual crystallographic sites. Such understanding is important to answer some fundamental questions on the origin of magnetism in these materials, such as whether the MAX phases magnetic response originates from localized moments or itinerant magnetism. Neutron diffraction can uniquely identify the existence and value of long range magnetism in a crystallographic site of a particular phase. Using this method on (Cr_0.96Mn_0.04)₂GeC we show, for the first time, experimental evidence for long range magnetic ordering in bulk MAX phase.