Negative magnetoresistance in a mixed-valence La0.6Y0.1Ca0.3MnO3: Evidence for charge localization governed by the Curie-Weiss law
Sergeenkov S., Bougrine H., Ausloos M., Gilabert A.
PACS: 75.70.Pa, 71.30.+h, 72.15.Gd
Colossal negative magnetoresistance Ap observed in øÁÏ.ÅõÏÌóÁÏ.ÚíÐïÚ at ÷ = 1Τ shows an unusual, nearly perfect symmetry (around the peak temperature To = 160 K) suggestive of Curie-Weiss dominated transport mechanism in this material both above and below the field-dependent Curie temperature T<? = ToAttributing this symmetry to strong magnetic fluctuations below Tq (which are triggered by the Y substitution and cause a "bootstrap" destruction of the ferromagnetic phase), the data are interpreted in terms of the nonthermal spin hopping and magnetization Μ dependent charge carrier localization scenario leading to Ap = -p, (l e—iM^ with M(T, B) = CB/\T-TC{B)\". The separate fits through all the data points above and below Tq yield C+ ~ 2C~ and u+ ~ ν~ 1, in agreement with the predictions of the Landau mean-field theory.
Home
![](/ps/912/article_13981_800_head.png "Colossal negative magnetoresistance <b><i>Ap </i></b>observed in øÁÏ.ÅõÏÌóÁÏ.ÚíÐïÚ at <b><i>÷ = </i></b>1Τ shows an unusual, nearly perfect symmetry (around the peak temperature To = 160 K) suggestive of Curie-Weiss dominated transport mechanism in this material both above and below the field-dependent Curie temperature T<? = <b><i>To</i></b>Attributing this symmetry to strong magnetic fluctuations below <i>Tq </i>(which are triggered by the <i>Y </i>substitution and cause a "bootstrap" destruction of the ferromagnetic phase), the data are interpreted in terms of the nonthermal spin hopping and magnetization <i>Μ </i>dependent charge carrier localization scenario leading to <b><i>Ap = -p, </i></b>(l <b><i>e—i<sup>M</sup>^ </i></b>with M(T, <b><i>B) = CB</i></b><i>/\T<b>-T<sub>C</sub>{B)\".</b></i> The separate fits through all the data points above and below <i>Tq </i>yield C+ ~ <b><i>2C~ </i></b>and <b><i>u+ ~ ν</i></b>~ 1, in agreement with the predictions of the Landau mean-field theory.")