Strain-mediated effects of oxygen deficiency and variation in non-Fermi liquid behavior of epitaxial PrNiO_3−δ thin films

Abstract

To understand the effects of oxygen variation in combination with different strains in perovskite nickelates, three sets of PrNiO 3−δ thin films S 1 , S 2 and S 3 were deposited on (0 0 1) oriented single-crystal wafers of SrTiO 3 , LSAT [(LaAlO 3 ) 0.3 (Sr 2 TaAlO 6 ) 0.7 ] and LaAlO 3 , respectively. Two sets of films, S 1 and S 2 , have tensile strain whereas the films of S 3 show compressive strain. For each set, two thin films of fixed thickness (5 nm) were deposited; one film was annealed in situ in oxygen partial pressure just after deposition, the other film was not annealed. The difference in oxygen stoichiometry caused a different state of epitaxial strain in the films. So, the strain was induced in the films due to lattice mismatch with substrate, which modified due to oxygen deficiency. These films show non-Fermi liquid (NFL) behavior in the metallic state. The fitting parameters to power-law equation show a systematic tuning of NFL fitting parameters because of variations in strain. Our results show that not only lattice mismatch induced strain, but also oxygen stoichiometry are crucial parameters in changing the state of strain and hence the NFL behavior and electronic properties of perovskite nickelates.

Optimization of the Growth Process of Double Perovskite Pr2−δNi1−xMn1+xO6−y Epitaxial Thin Films by RF Sputtering

“…The dependence of ρ (T) can be well fitted by using the thermal activation mechanism, described by the Arrhenius law (see Figure 8 b) where is a constant, E 0 is the required activation energy for the conduction process generally at high temperatures, and K B is the Boltzmann constant [ 40 , 41 ]. This model can explain the thermally generated charge-transport behavior and activation type mechanism in the insulating state [ 42 ]. The fitting of the Arrhenius model was found in a temperature range from 300 K to 195 K. The extracted value of the activation energy E 0 for our PNMO film was found to be E 0 ≈ 0.18 ± 0.1 eV, which is comparable to that of the cation-ordered RNMO compounds [ 40 , 42 , 43 ].…”

“…This model can explain the thermally generated charge-transport behavior and activation type mechanism in the insulating state [ 42 ]. The fitting of the Arrhenius model was found in a temperature range from 300 K to 195 K. The extracted value of the activation energy E 0 for our PNMO film was found to be E 0 ≈ 0.18 ± 0.1 eV, which is comparable to that of the cation-ordered RNMO compounds [ 40 , 42 , 43 ].…”