Crossover between Kondo and electron–electron interaction effects in La_0.75Sr_0.20MnO₃manganite doped with Co impurities?

Abstract

The resistivity minimum in manganites is still under debate. Recent publications discussed two possible scenarios: (i) electron–electron interaction in weak disordered systems and (ii) charge carriers tunnelling between antiferromagnetic coupled grains. In order to resolve this puzzle, we present a systematic study on the electrical resistivity, ρ(T), which was carried out in ceramic samples of La0.75Sr0.20MnO3 and La0.75Sr0.20Mn1−cCocO3 manganites over the temperature ranges 0.4–60 K and 4–60 K respectively. All compounds show a minimum in the resistivity at a characteristic temperature Tmin, which in the Co-doped samples shifts towards higher temperatures as the Co concentration increases. Tmin varies approximately as c1/3. The application of an external magnetic field shows that the Tmin decreases linearly as the field increases, and above 0.7 T remains field independent. In magnetic fields, where Tmin is constant, Tmin varies as . For temperatures below Tmin the resistivity data can be fitted either with a or with a −lnT function, while for temperatures above the minimum the resistivity follows both a T3 and a T5/2 dependence. We believe that there is a crossover between a ‘Kondo-like’ scattering process and the 3D electron–electron interaction effects enhanced by disorder.

Effect of Eu doping on structural and magneto-electrical properties of La0.7Ca0.3MnO3 manganites

“…In addition to structural changes seen by this kind of doping, an increase in resistivity and a decrease of the metal-insulator transition temperature are revealed. As observed in recent studies [23][24][25][26], a minimum in resistivity was also obtained in the present work. In order to explain the origin of this behaviour, the experimental data is analyzed by using different mechanisms, such as spin dependent transport mechanism, Kondo like scattering and quantum correction to conductivity [27][28][29].…”

Effects of ferroelectric-poling-induced strain on the quantum correction to low-temperature resistivity of manganite thin films

“…The low-temperature resistivity minimum and upturn in polycrystalline samples was found to be suppressed by magnetic field and was interpreted in terms of the intergrain spin-polarized tunneling through grain boundaries. [1][2][3] The intergrain tunneling model was experimentally confirmed by Rozenberga and co-workers 1,2 and Xu et al 3 The low-temperature resistivity upturn in intrinsically disordered ͑e.g., magnetic/charge phase separation͒ samples [4][5][6] was attributed to the Kondo-type effect which was previously observed in dilute magnetic alloys. 7 It is noteworthy that Lee et al 8 theoretically pointed out the possible presence of quantum corrections to conductivity ͑QCC͒ in manganite single crystals and thin films.…”

Structure and electrical resistivity of La1−xBaxMnO3 (0.25≤x≤0.35) perovskites

“…Henceforth, the lowtemperature transport properties of the doped manganites may reflect the intrinsic mechanism of the systems. Beside the distinct low-field magnetoresistance at low temperatures, experimental reports provide evidence for the existence of the resistivity minimum at low temperatures in the manganites, no matter the polycrystalline, the quality film, or the single crystal, which is similar to the Kondo effect [18,19]. On the other hand, for the strongly correlated system, there may be another contribution arising from the renormalization of the effective electron-electron interactions, which can modify the density of the states at the Fermi energy and enhanced the resistivity [20,21].…”