Temperature and Magnetic Effects on the Work Function of a Ni(100) Surface

The influence of ferromagnetism on the work function (WF) was studied by measuring the contact potential difference of a Ni(100) face, with an accuracy of ±0.5 meV. A decrease of the WF with temperature (approximate coefficient: -1.83×10 -4 eV/°C) and an anomalous change near the Curie point were found. By extrapolation from the paramagnetic region, the magnetic effect on the WF was estimated to be 2∼3 meV. These experimental results are explained as the combined effect of thermal expansion and spontaneous volume magnetostriction.