Magnetic properties of Mn-doped armchair ZnO nanotubes: a Monte Carlo study

The magnetic properties of a Mn-doped armchair ZnO nanotube have been studied using Monte Carlo simulation. The variation of zero-field-cooled and field-cooled magnetisation with reduced temperatures for different values of the dilution x (where x is the Mn concentration: Zn_1?xMn_xO) are given. The freezing temperatures and magnetisation vs. crystal field are calculated for different dilutions x. Finally, the hysteresis loops for different dilutions and temperatures are given for a fixed reduced temperature and crystal field. Superparamagnetic behaviour is observed for small values of x and low temperatures.