Compositional Dependence of Epitaxial L 1 0 ‐Mn x Ga Magnetic Properties as Probed by 57 Mn/Fe and 119 In/Sn Emission Mössbauer Spectroscopy

The magnetic properties of MnxGa alloys critically depend on compositionx, andthe atomic-scale origin of those dependences is still not fully disclosed. Molecularbeam epitaxy has been used to produce a set of MnxGa samples (x¼0.7÷1.9)with strong perpendicular magnetic anisotropy, and controllable saturationmagnetization and coercivefield depending onx. By conducting57Mn/Fe and119In/Sn emission Mössbauer spectroscopy at ISOLDE/CERN, the Mn and Gasite-specific chemical, structural, and magnetic properties of MnxGa are inves-tigated as a function ofx, and correlated with the magnetic properties asmeasured by superconducting quantum interference device magnetometry.Hyperfine magneticfields of Mn/Fe (either at Mn or Ga sites) are found to begreatly influenced by the local strain induced by the implantation. However,In/Sn probes show clear angular dependence, demonstrating a huge transferreddipolar hyperfinefield to the Ga sites. A clear increase of the occupancy of Galattice sites by Mn forx>1 is observed, and identified as the origin for theincreased antiferromagnetic coupling between Mn and Mn at Ga sites that lowersthe samples’magnetization. The results shed further light on the atomic-scalemechanisms driving the compositional dependence of magnetism in MnxGa.