Colossal magnetoresistance (CMR) is a large decrease of electrical resistivity when a magnetic material is subjected to an external magnetic field. This effect has applications in the magnetic switch, spin valve, magnetic memory, and spintronic technologies. CMR has been a subject of intense research, and its mechanism has been identified to be a combination of mixed-valence and double-exchange interactions. Such effects are common in oxide materials made with manganese (manganates). In this work, our postdoc, Dr. Zhi-Cheng Wang, has changed the paradigm of CMR by synthesizing a material with the largest observed CMR in single crystals, but without mixed-valence, double-exchange, manganese, and oxygen.
The exact mechanism of this new type of CMR is yet to be understood, but the evidence presented in our article points toward the importance of magnetic fluctuations and spin canting in the material. We have presented a new pathway to discovering new compounds with CMR effect that are both applicable in technology and exciting in fundamental research. Two undergraduate researchers, Renee Nichols and Kemal Atay, and two graduate students, Xiaohan Yao and Jared Rogers, have also participated in this research.
