Role of Dy 4 f electrons on magnetic coupling and reorientation in DyFeO 3 .

Spin reorientation transition is an ubiquitous phenomenon observed in magnetic rare earth orthferrites RFeO 3 , which has garnered significant attention in recent years due to its potential applications in spintronics or magnetoelectric devices. Although a plenty of experimental works suggest that the magnetic interaction between R 3+ and Fe 3+ spins is at the heart of the spin reorientation, but a direct and conclusive theoretical support has been lacking thus far, primarily due to the challenging nature of handling R 4 f electrons. In this paper, we explored DyFeO 3 as an example by means of comprehensive first principles calculations, and compared two different approaches, where the Dy 4 f electrons were treated separately as core or valence states, aiming to elucidate the role of Dy 4 f electrons, particularly in the context of the spin reorientation transition. The comparison provides a solid piece of evidence for the experimental argument that the Dy 3+ -Fe 3+ magnetic interactions play a vital role in triggering spin reorientation of Fe 3+ moments at low temperatures. The findings revealed here not only extend our understanding on the underlying mechanism for spin reorientation transition in RFeO 3 , but also highlight the importance of explicit description of R 4 f electrons in rationally reproducing their structural, electronic and magnetic properties.