Tunneling Spectroscopy Studies of Two-Dimensional van der Waals Magnets

Two-dimensional magnetic materials have opened new avenues for scientific exploration and innovative device design. Here we present the properties of ferromagnetic Mn(Bi_0.88,Sb_0.18)₆Te₁₀ by combining magneto-transport and transport tunneling spectroscopy. Planar tunnel junction devices are made through synthesis, exfoliation, and the van der Waals dry transfer technique. We probe the density of states and inelastic excitations near the sample’s surface in a wide range of temperatures and in-plane and perpendicular magnetic fields. At zero magnetic field, we observe multiple strongly T-dependent resonant peaks in the tunneling spectra of Mn(Bi_0.88,Sb_0.18)₆Te_10. The magnetic field dependence of some of the features points to the development of Landau levels of Mn(Bi_0.88,Sb_0.18)₆Te₁₀ , which are absent in control samples. We discuss the implications of our results using input from band structure calculations and ARPES. The tunnel junction technique is also applied to an anti-ferromagnet CrSBr. We make connections between transport, tunneling spectra and the magnetic phase diagram of this material.