1. Researchers at the University of Basel have investigated how to better understand the ferromagnetic properties of electrons in 2D semiconductor molybdenum disulfide. 2. They discovered that the energy required to flip a parallel-aligned electron spin can be measured in a surprisingly simple way. 3. The study, published in 'Physical Review Letters', determined the exchange energy necessary to reverse a single electron spin in this ferromagnetic state, indicating the material's stable ferromagnetism.