First-Principles Study on Possible Half-Metallic Ferrimagnetism in Double Perovskites Pb2XX′O6 (X = Ti,Zr, Hf,V, Nb and Ta,X′ = Tc,Ru, Os and Rh)

Pb-based double perovskite compounds with chemical formula Phey have abundant physical properties in the spintronic field. Among all the features, the spin interaction of half-metallic (HM) is regarded as an important performance measure because of its high potential in spintronic devices. In this research study, we calculate density of state (DOS) to investigate possible half-metal candidates by executing structural optimization based on the method of generalized gradient approximation (GGA) and strong correlation effect (GGA + U). Furthermore, following the earlier methods by calculating and comparing energy difference of various compounds with the four initial magnetic states: ferromagnetic, ferrimagnetic, antiferromagnetic and nonmagnetic, we can determine which magnetic state is more stable. Results indicate that there are 13 possible ferrimagnetic HM candidates in these combinations, including Pb₂NbTcO₆, Pb₂TaTcO₆, Pb₂TiRuO₆, Pb₂ZrRuO₆, Pb₂HfRuO₆, Pb₂VRuO₆, Pb₂NbRuO₆, Pb₂TadRuO₆, Pb₂ZrOsO₆, Pb₂HfOsO₆, Pb₂VOsO₆, Pb₂ZrRhO₆ and Pb₂HfRhO₆ under GGA and GGA + U schemes. The stability of analysis by analyzing the energy gap illustrates that all 13 possible candidates are half metals and ferrimagnetic states, so our studies could provide guidelines for scientists to fabricate new double perovskites in future.