Investigating the Cause of Quantum Phase Transition in Gd Intermetallic Compounds

Abstract

Quantum phase transition (QPT), a consequence of quantum critical point (QCP), was considered for the suppression of unstable double phase transition of Gd intermetallic compounds to the paramagnetic state, despite the lack of both hybridization and crystal field effect (CFE) which are fundamental in the existence of QCP. The phenomenon is supposed to be due to the exchange fluctuation character in terms of competition between exchange and kinetic energies of conduction electrons (c.e) during the strong spin-induced polarization of c.e defined by DFT calculations. All electronic structure calculations in this work were carried out by WIEN2K package in the framework of PBE approximation. We found evidences on the tuning of K _F in direction to shift the topological magnetic ions to minimize the correlation length R _C =2K _F R _{i j} at the critical point. At this point, the system is close to the critical value near the double ferromagnetic-antiferromagnetic percolation threshold. Experiment shows that the broad dynamic instability of the Curie temperature can lead the sample behavior to the antiferromagnetic state by induced stress motion due to the sample shape (powder to needle) and to the paramagnetic state by imposing magnetic field. The calculated cohesive energy implies that the exchange energy can adopt the magneto-crystalline system as a more stable symmetrical configuration by developing much more negative cohesive energy depending on the yttrium compound in direction to reduce the bulk modulus, which results in the vanishing of antiferromagnetic ordering. We found evidences on the quantum phase (QP) coherence of the Fermi wave vector λ _F, which contributes to the shear stress σ in direction to stabilize both magnetic and crystalline structures in the paramagnetic state.