Abstract
We describe a disordered local moment theory for long-period magnetic phases and investigate the temperature and magnetic field dependence of the magnetic states in the heavy rare earth elements (HREs), namely, paramagnetic, conical and helical antiferromagnetic (HAFM), fan, and ferromagnetic (FM) states. We obtain a generic HRE magnetic phase diagram which is consequent on the response of the common HRE valence electronic structure to f-electron magnetic moment ordering. The theory directly links the first-order HAFM-FM transition to the loss of Fermi surface nesting, induced by this magnetic ordering, as well as provides a template for analyzing the other phases and exposing where f-electron correlation effects are particularly intricate. Gadolinium, for a range of hexagonal, close-packed lattice constants c and a, is the prototype, described abinitio, and applications to other HREs are made straightforwardly by scaling the effective pair and quartic local moment interactions that emerge naturally from the theory with de Gennes factors and choosing appropriate lanthanide-contracted c and a values.
Highlights
Close scrutiny and an ab initio description of the magnetism of rare earth materials are motivated by its increasing importance for many applications as well as the fundamental interest of the strongly correlated f electrons underpinning it
When cooled through Tc, Gd’s paramagnetic (PM) phase undergoes a secondorder transition to a ferromagnetic (FM) state, whereas, at TN, Tb, Dy, and Ho form incommensurate, helical antiferromagnetic (HAFM) phases where the magnetization spirals around the crystal c axis
This is in sharp contrast to Tb [3,11,12,13], Dy [4,5,6,7,14], and Ho [8,10] above Tt, which first distort their HAFM order before undergoing a first-order transition into a fan magnetic structure followed by a second-order transition to a FM state with a further increase in the magnetic field
Summary
Close scrutiny and an ab initio description of the magnetism of rare earth materials are motivated by its increasing importance for many applications as well as the fundamental interest of the strongly correlated f electrons underpinning it. This has resulted in the construction of a universal crystallomagnetic phase diagram which links the magnetic ordering that emerges from the PM state to the specific c and a lattice parameters of a heavy lanthanide system [16,18].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
