Spin Fluctuation Effect on Electrical Resistivity of La_0.8Ca_0.2MnO₃ Manganite Nanoparticles

Abstract

The electrical resistivity ðT Þ of La 0:8 Ca 0:2 MnO 3 manganite nanoparticles (particle size 18 nm and 70 nm) signi¯cantly depends on temperature and size of nanoparticles. ðT Þ of 70 nm La 0:8 Ca 0:2 MnO 3 manganite exhibits metallic phase in low temperature regime (T < 250 K), develops a maxima near 250 K and decrease with T at high temperatures (250 K < T < 300 K). However, the ðT Þ of 18 nm La 0:8 Ca 0:2 MnO 3 manganite shows insulating phase in overall temperature regime, where resistivity decrease with temperature. The resistivity in metallic phase is theoretically analyzed by considering the strong spin°uctuations e®ect which is modelled using Drude-Lorentz type function. In addition to the spin°uctuation-induced contribution the electron-phonon and electron-electron eÀe ðT Þ ¼ BT 2 contributions are also incorporated for complete understanding of experimental data. The contributions to the resistivity by inherent acoustic phonons ( ac ) as well as high frequency optical phonons ( op ) were estimated using Bloch-Gruneisen [BG] model of resistivity. It is observed that the resistivity contribution due to electron-electron interaction shows typical quadratic temperature dependence. Resistivity in Semiconducting/insulating phase is discussed with small polaron conduction (SPC) model. Finally the theoretically calculated resistivity compared with experimental data which found consistent in wide range of temperature.

Scaling like behaviour of resistivity observed in LaNiO3thin films grown on SrTiO3substrate by pulsed laser deposition

“…Given the above discussion on appearance of magnetic order in LNO/STO hybrid structure, it is quite reasonable to assume that the observed temperature behaviour of resistivity can be attributed to the manifestation of strong long-range spin fluctuations with a characteristic energy hω sf ≃ k B T sf corresponding to low-energy spin dynamics spectrum measured by inelastic neutron scattering experiments. It should be pointed out that a rather significant scattering of conduction electrons by spin fluctuations is well documented for many different materials, see, e.g., [19][20][21][22][23][24][25][26] and further references therein. Recently, we suggested a simple phenomenological model based on the resonant like features of SDW type spectrum which result in the observed universal temperature dependence of the resistivity, see [27] for more discussion.…”

“…It should be pointed out that a rather significant scattering of conduction electrons by spin fluctuations is well documented for many different materials, see, e.g. [19][20][21][22][23][24][25][26] and further references therein. Recently, we suggested a simple phenomenological model based on the resonant like features of SDW type spectrum which result in the observed universal temperature dependence of the resistivity, see [27] for more discussion.…”