Local heating effect in point-contact spectroscopy for magnetic metals of Ni and ?-Mn

Abstract

The current-voltage characteristics at a homojunction point-contact of ferromagnetic Ni single crystal and antiferromagnetic ct-phase Mn polycrystalline metal have been measured at 4.2 K. Several singularities in the first and second derivative of I-V curves are observed at specific bias voltages for both metals. Taking into account the observed temperature dependence of the bulk electrical resistivity and thermal conductivity (and thus mean free path of electrons), we have performed computer simulations of these nonlinear I-V characteristics based on a modified "local heating model" and compared with the results by a traditional "spherical spreading-out" (SSO) model When a constant additive correction to the bulk resistivity near a contact interface is incorporated, our calculated curves are in good agreement with the experimental results.