Double metal–insulator transitions and MR in La0.67Ca0.33Mn1−xRuxO3 (x⩽0.10): a qualitative understanding in light of possible magnetic phase separation

Abstract

We report results of the magnetotransport measurements on La 0.67 Ca 0.33 Mn 1Àx Ru x O 3 (0pxp0.1) compounds in the light of proposed magnetic phase separation in our previous work wherein two metal to insulator transitions (MITs) were reported (J. Magn. Magn. Mater. 257 (2003) 195). With the application of magnetic field, a significant reduction in resistance and a shift in MITs to higher temperatures but with different rates are observed. The temperature dependent magnetoresistance (MR) exhibits two maxima, a pronounced one at higher temperature and a shallow one at low temperature, corresponding to the two MITs. The peak value of MR at high temperature MITs (H ¼ 5 T) does not change systematically with Ru concentration. The low temperature MR peak becomes perceptible for xX0:03 and shows a nominal enhancement with Ru concentration. The double maxima, both exhibiting MR phenomena in the magnetotransport properties of Ru-doped manganites are analysed within the context of magnetic phase separation. r

Effect of Ru–Mn redox interactions on the hole carrier density in pulsed electron deposited La1−xPbxMn0.8Ru0.2O3(0.2≤x≤0.4) thin films

“…The low temperature MR decreases and the transition peaks become sharp; indicating that the phase separation does not dominate. This feature is completely different from the two distinct T MIT maxima observed with large low temperature MR for Ru doped La 0.66 Ca 0.33 MnO 3 [26].…”

Structural and Magnetic Properties of Ba0.7Sr0.3Ru1−xMnxO3 Hexagonal Perovskites

“…[7,8,9,10] Ru and Mn can be substituted for each other in perovskite-type oxides and several series have been investigated such as CaMn 1Àx Ru x O 3 , [11] SrMn 1Àx Ru x O 3 , [12,13] and Ln y A 1Ày Mn 1Àx Ru x O 3 (Ln = lanthanide; A = Ca, Sr). [14][15][16][17] Ru doping induces ferromagnetism and metallicity, and suppresses the charge-ordered state of manganites. The origin of these effects has been debated, but is clearly related to the electronic states of Ru and Mn.…”