Zhao Liu, Monash
We demonstrate the occurrence of robust itinerant ferromagnetism in Mott-Hubbard systems at both low and high doping concentrations. Specifically, we study the effect of hole doping on the experimentally synthesized LaCrAsO via first-principles calculations and observe that the parent G-type antiferromagnetism vanishes quickly at low doping concentration (x ~ 0.20) and the system becomes ferromagnetic metal due to the canonical double exchange (CDE) mechanism. As x continues to increase, the onsite energy difference between Cr 3d and As 4p orbitals decreases and the system transitions to a ferromagnetic negative charge-transfer energy metal.
Therefore, the itinerant ferromagnetism doesn’t terminate as the CDE mechanism usually predicts. Furthermore, our calculations reveal that both nearest and next-nearest ferromagnetic exchange coupling strengths keep growing with x, showing that ferromagnetism caused by negative charge-transfer energy state is “stronger” than that of CDE picture. Our work not only unveils an alternative mechanism for itinerant ferromagnetism, but also has the potential to arouse immediate interest among experimentalists.
About the presenter
Zhao is a Research Fellow in CI Nikhil Medhekar‘s group. After completing his PhD in 2018, Zhao is exploring magnetic materials and topological materials theoretically. He aims to understand the integration of magnetism and topology in 2D materials. This work fits the FLEET Research Theme 1, Topological Materials.