On the electrical properties of polycrystalline delafossite-type AgNiO2

Pinball liquid phase from Hund's coupling in frustrated transition-metal oxides

“…Above the coherent-incoherent crossover temperature T * , quasiparticles are destroyed due to the scattering of the itinerant carriers by the unscreened pin moments, which has several experimental manifestations. The measured resistivity indeed displays typical Fermi-liquid behavior ρ ∼ T 2 above the Néel temperature T N = 20 K, albeit with anomalously large absolute values ( 1 m cm) [14][15][16][17], which crosses over to a (sub)linear T dependence [16] at temperatures above T * 150 K. At lower temperatures, the resistivity undergoes a sharp drop below T N which has been associated [10,19] with the suppression of such scattering. The Seebeck coefficient increases linearly with temperature up to about 100 K, as expected in a metal, but then it reaches a maximum around T * and changes sign at 260 K [14,15].…”

“…The material is therefore metallic throughout the charge-ordered phase, which contrasts with the situation in nonfrustrated perovskite nickelates [12,13], RNiO 3 , where charge order invariably leads to an insulating behavior. The high values of the electrical resistivity and its anomalous temperature dependence in AgNiO 2 [14][15][16][17], however, indicate bad metallic behavior, also supported by the observation of a large pseudogap in photoemission experiments [18], an anomalous Seebeck coefficient [14,15], and a large specific-heat coefficient [19].…”

Three-dimensional magnetism and coupling to the conduction electrons in PdCrO2

“…5 Takatsu and co-workers find that the magnetic Bragg peaks in neutron scattering are rather broad and halfinteger l (1/3,1/3,l) and (2/3,2/3,l) peaks are found in addition to the integer l peaks. 1 In any case, PdCrO 2 is a particularly interesting system because like its sister compound PdCoO 2 it is conducting, 6 and has a very large conductivity anisotropy. 7 This offers an opportunity to study the interplay between frustrated magnetism and charge carriers in a near two dimensional metal.…”

Synthesis and crystal structure of AgYbO2

“…Table 4 compares both the a-and c-lattice parameters of AgYbO 2 with those of other silver delafossites reported. 6), 13) The c axis of AgYbO 2 is the shortest in the series containing an Ag ＋ ion in the A site. Haas and Kordes suggested that the c axis of delafossites containing lanthanoid ions is shorter than that of others.…”