Nitrogen rich type Ib HPHT grown synthetic diamonds were investigated following large area irradiation of the samples using 2.2 MeV protons. Studies on possible magnetic properties induced after the irradiation were performed using a SQUID magnetometer. Magnetisation measurements of pristine (unirradiated) control samples revealed a superparamagnetic-like signal at 300 K. After the proton irradiation, a Curie-like paramagnetic curve was observed for thermal cycles at an applied magnetic field of 2 kOe which exhibits a transition at temperatures around 50-55 K, with hysteretic behaviour below these temperatures.

This research was funded by the DST-NRF Centre of Excellence in Strong Materials, the National Research Foundation and the University of the Witwatersrand in South Africa.