Much of our current technology was enabled by our understanding of semiconductors, whose electrons behave collectively in a similar way as how an individual electron does. In contrast, a hallmark of quantum materials is the emergence of unusual collective electronic behaviors that give rise to fascinating phenomena with unique potential for novel applications. A posterchild is the phenomenon of high-temperature superconductivity, by which materials carry electric currents without dissipation at relatively high temperatures. An important clue to elucidate this highly debated state of matter comes from the observation that it tends to appear in close proximity to the very different phenomenon of magnetism. These two states seem to live a love-hate relationship, displaying a mixture of competition and cooperation. In this talk, I will discuss new and exciting progress on this problem enabled by recent Quantum Monte Carlo simulations of an effective low-energy model.