Localized level hopping transport in La(Sr)CrO3

Hole-induced insulator-to-metal transition inLa1−xSrxCrO3

“…The RT resistivities of the epitaxial films are at least an order of magnitude lower than those for polycrystalline samples at comparable Sr doping levels except for x = 0, for which the MBE-grown LCO is much more resistive than the analogous powder samples. 13,14 Moreover, we find that unlike transport data for polycrystalline LSCO films taken from 300K to 2000K, 13,14 our data taken from 100K to 330K fit equally well to small polaron hopping ( exp ) ) and to band conduction ( exp )) models. (See Fig.…”

“…From the relatively spares literature available, it appears that LSCO behaves rather differently than analogous LSMO systems. No insulator-to-metal transition has been found even at the highest reported Sr doping level (x = 0.5), [13][14][15][16][17][18] in contrast to La 1-x Sr x MO 3 (M = Ti, V, Mn and Co), which exhibit such a transition at x ≤ 0.17. [6][7][8] Previous investigations of LSCO have utilized polycrystalline powder samples.…”

“…Likewise, Karim and Alfred 14 made an analogous set of samples with x up to 0.4, measured transport from 300K to 2000K, and reported room-temperature resistivities ranging from ~500…”

Magnetotransport and magnetic properties of weak ferromagnetic semiconductors: Ca doped LaCrO3

“…14 To provide an energy gap E g that gives a measure of the thermal excitation needed for conduction, we fit the data to ͑T͒ = exp͑E g / k B T͒. The data were fitted in the temperature range 200Ͻ T Ͻ 500 K; straight-line behavior was observed in this temperature range and the obtained energy gaps values are in the same range as those reported 6 for La 1−x Sr x CrO 3 . We believe that electrical resistivity data on single crystals or high-quality thin films are necessary to fully investigate the electrical conduction properties of this system.…”

“…The dc electrical transport of La 1−x Sr x CrO 3 ͑0 Ͻ x Ͻ 0.40͒ is thermally activated in the range 300Ͻ T Ͻ 2000 K with activation energies between 0.11 and 0.19 eV and temperature-dependent behavior consistent with conduction by small polarons. 5,6 LaCrO 3 is an interesting compound with transition metal ions that have three electrons in the 3d shell, which leads to total spin S = 3 2 . The antiferromagnetic structure is G type, whereby each Cr 3+ ion is antiferromagnetically coupled to its neighbor.…”