Metallic state induced in Eu2Ru2O7 by hole creation and orbital overlap in the t2g bands

Abstract

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Structural disorder, magnetism, and electrical and thermoelectric properties of pyrochlore Nd2Ru2O7

“…Pb 2 Ru 2 O 6.5 , Tl 2 Ru 2 O 7−y ), as these contain either A-site ions of different formal charge in the case of Pb 2+ , or have [49]. Values of electrical resistivity were taken from references [1,3,22,26,50,51,52,53]. contributions from overlap between empty 6s states and filled states, as in the case of Tl 3+ .…”

“…Even an isovalent substitution of Ln 3+ by Bi 3+ may not allow straightforward comparison; structural studies of Bi 2 Ru 2 O 7 have shown that Bi 3+ atoms are off-centred due [50]. Values of electrical resistivity were taken from [1,3,20,26,[51][52][53][54].…”

Ruthenium-europium configuration in the Eu2Ru2O7 pyrochlore

“…Our transport data obtained in the intermediate and high field regimes follow a Mott Variable Range Hopping (VRH) or Efros-Shklovskii mechanism. 32 Since the e' g 3 electrons are highly localized, a soft Coulomb gap Δ c of around ~ 0.29 eV can be interpreted as an increase in the density of states close to and above the E F due to the excited states from the extrinsic Eu 3+ .…”

“…In Eu 2-x Ca x Ru 2 O 7 and Eu 2 Ru 2-x Re x O 7 a delicate balance between the localized and delocalized states evolves towards a metal-like behaviour. 9,32 On the other hand, Tl 2 Mn 2 O 7 and Tl 2 Ru 2 O 7 show colossal magnetoresistance and spin gap formation, respectively. 26,33…”

“…The orbitals dxz, dyz and 5s 1 form the conduction band (nonbonding state).This configuration allows the formation of a valence band with four σ bonds (each bond consists of two electrons, one from the metal and one from the O 48f ) and two π bonds. The theory also shows that electron pairs involved in a π bond are provided by the sp 3 32 Since the e' g 3 electrons are highly localized, a soft Coulomb gap Δ c of around ~ 0.29 eV can be interpreted as an increase in the density of states close to and above the E F due to the excited states from the extrinsic Eu 3+ .…”