Synthesis and magnetic characterization of epitaxial MnGe thin films on Si(111)

Abstract

Magnets with broken inversion symmetry possess a chiral interaction that leads to twisting of the magnetic structures. MnGe is a much less understood member of the B20 family of chiral magnets, in part due to the challenges in synthesizing this metastable material. While others have grown MnGe thin films on magnetic template layers, it is demonstrated that a paramagnetic template layer of B20 CrSi serves as a good epitaxial template for nucleation and growth of MnGe. Single-phase MnGe(111) thin films were grown with thicknesses below 40nm and interfacial roughnesses less than 0.6nm. Magnetometry measurements were conducted and reveal that the ground state is a helical modulation which is distorted into a helicoidal or conical state. Magnetotransport reveals signatures that are not observed in magnetometry, and indicates that the magnetic structure may be more complicated below 60K. Neutron or resonant X-ray scattering experiments are necessary to resolve this.