UC Davis

This dissertation details my exploration of two compounds: LaCrGe3 and LaCrSb3. While their names differ by only two letters, and therefore their compositions by only one element, they are quite different. The relevant question to ask about these two ferromagnetic systems is: “what happens when their ferromagnetism is suppressed?" Although the magnetic phase diagram of LaCrGe3 under pressure has previously been charted, there are aspects of its rich temperature-pressure-magnetic field phase space that are contested. In particular, through a meticulous study of its magnetic domain behavior, I provide evidence in favor of the existence of multiple ferromagnetic states in LaCrGe3. We find that investigating domain behavior can lead to a more accurate way of characterizing new materials and perhaps a method of probing crossovers between ferromagnetic states. On the other hand, the ferromagnetism of LaCrSb3 is relatively robust to pressure. Therefore, I use Fe substitution to suppress its Curie temperature and discover the first reported magnetic phase diagram of its kind—one with an avoided quantum tricritical point. The LaCr1-xFexSb3 system has a temperature-chemical substitution-magnetic field phase diagram that is ripe with magnetic features for closer examination. Further study of both materials will likely lead to additional discoveries in the world of magnetism.