Colossal Magnetoresistance of Ferromagnetic Manganites: Structural Tuning and Mechanisms

Estimation of the charge carrier localization length from Gaussian fluctuations in the magneto-thermopower ofLa0.6Y0.1Sergeenkov1, Bougrine2, Ausloos3 et al. 1999Phys. Rev. B114240View full textAdd to dashboardCite

“…(18), B + exp , T * = 170K, and just obtained z, we get E 0 k /JS = 2.5(n i /n e ) which in turn brings about T C = 195K for the Curie temperature (this value falls into the reported range of the FM transition temperatures for this class of manganites [5][6][7][8] ). Using this temperature and assuming S = 2 for an effective Mn spin, we can estimate the value of the exchange energy J (via the mean-field expression for the critical field H 0 = 3k B T C /2Sµ B ).…”

“…Furthermore, the influence of magnetic fluctuations on electron-spin scattering near T MI is expected to be rather important, for they can easily tip a subtle balance between magnetic and electronic processes in favor of either charge localization or delocalization. Besides, the observable difference between the two critical temperatures (usually attributed to the quality of a particular sample used [5][6][7][8] ) is ascribed to the random nonmagnetic scattering which is highly responsible for the magnitude of the observable GMR. 13 On the other hand, in view of its carrier charge (and density) sensitive nature, thermopower (TEP) measurements could complement the traditional MR data and be used as a tool for probing the field-induced delocalization of the carriers.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] In the doping range 0.2 < x < 0.5, these compounds are known to undergo a double phase transition from paramagnetic (PM) insulator (I) to ferromagnetic (FM) metal (M) state characterized by the Curie temperature T C and the charge carrier localization temperature T MI , respectively. The so-called giant magnetoresistivity (GMR) exhibits a sharp peak around T MI , while below T C the system acquires a spontaneous magnetization accompanied by a giant magnetic entropy changes.…”

Low temperature synthesis, and magnetic and magnetotransport properties of a (La1 xLux)0.67Ca0.33MnO3(0 x 0.12) system

“…However, the resistivity decreases at all measured temperatures with increasing field. This has been ascribed to the strong spin disorder inside the grains by Damay et al 27 But Fontcuberta et al 34 Such type of field response has also seen in polycrystalline LSMO by many authors 38,39 .…”

“…8 in which the present data is plotted on the T C -t phase diagram of Terai et al 18 . 27 and Fontcuberta et al 34 In those cases, the low field slope also varies with composition and both the low field and the high field slopes increase with increasing Y content. However, the resistivity decreases at all measured temperatures with increasing field.…”