ﻻ يوجد ملخص باللغة العربية
The pyrochlore Eu$_2$Ir$_2$O$_7$ has recently attracted significant attention as a candidate Weyl semimetal. The previous reports on this compound unanimously show a thermally induced metal to insulator (MI) transition, concomitant with antiferromagnetic (AFM) long-range ordering of the Ir-moments below T$_textit{N} sim $120 K. However, there are contradictory reports concerning the slope d$rho/$dT of the resistivity plots ($rho$) in the metallic state above the metal-insulator (MI) transition, and the value of $rho$ in the insulating state, both of which show significant sample dependence. Here, we explore this issue by investigating six different Eu$_2$Ir$_2$O$_7$ samples with slightly varying Eu:Ir ratio. High-resolution synchrotron powder diffraction are done to probe minor variations in the cell parameters of the various Eu$_2$Ir$_2$O$_7$ samples investigated here. Specific heat (C$ _p $) and magnetic susceptibility of all the samples showed long-range antiferromagnetic ordering upon cooling below T$ _textit{N} sim $120 K. The transitions are, however, found to be smeared out for the off-stoichiometric samples. We show that the sign of d$rho/$dT above the metal-insulator (MI) transition is highly sensitive to the unit cell length, which, in turn, depends on the level of Eu-stuffing at the Ir-site. Samples with composition close to the ideal stoichiometry (Eu : Ir $ = $ 1) showed a change of sign of d$rho/$dT from negative to positive upon cooling below a certain temperature T $^*$ $>$ T$_textit{MI}$. With increasing Eu-stuffing T$ ^* $ decreased until a negative d$rho/$dT persisted without any sign change down to T$_textit{MI}$.
Electrons in the pyrochore iridates experience a large interaction energy in addition to a strong spin-orbit interaction. Both features make the iridates promising for realizing novel states such as the Topological Mott Insulator. The pyrochlore irid
We report a combined muon spin relaxation/rotation, bulk magnetization, neutron scattering, and transport study of the electronic properties of the pyrochlore iridate Nd2Ir2O7. We observe the onset of strongly hysteretic behavior in the temperature d
We present magnetization and Hall effect measurements on the pyrochlore iridate Nd2Ir2O7. Previous muon spin rotation measurements have shown that the system undergoes an unusual transition at T$_M$ = 110 K into a magnetic phase lacking long-range or
There are reasons to believe that the ground state of the magnetic rare earth pyrochlore Yb$_2$Ti$_2$O$_7$ is on the boundary between competing ground states. We have carried out $mathrm{textit{ab initio}}$ density functional calculations to determin
We report neutron diffraction measurements of the magnetic structures in two pyrochlore iridates, Yb2Ir2O7 and Lu2Ir2O7. Both samples exhibit the all-in-all-out magnetic structure on the Ir4+ sites below TN~ 150,K, with a low temperature moment of ar