Magnetotransport studies and mechanism of Ho- and Y-doped La0.7Ca0.3MnO3
Abstract
Transport properties of mixed-valence manganites of the type (La0.7-xRx)Ca0.3MnO3 where R=Ho (magnetic) and Y (nonmagnetic) have been investigated above the ferromagnetic transition temperature (TC). It is interesting to see that the Ho-doped compounds have less resistivity compared to the Y-doped compounds, although Ho and Y ions have almost the same ionic radii and hence lattice strain effect would be the same in both the cases. The internal magnetic field of Ho (μHoeff=10.5μB) is found to be responsible for this decrease in resistivity in Ho-doped compounds. Coupling of Ho magnetic moment to that of Mn has been confirmed by magnetization measurements. The resistivity data above TC fit well to the magnetic localization model proposed by Viret et al. [Phys. Rev. B 55, 8067 (1997); Phys. Rev. Lett. 75, 3910 (1995)] and the localization lengths thus obtained are reasonable. The localization lengths of the Ho-doped compounds are greater than that of Y-doped compounds of the same composition indicating that the coupling of the Ho moment with that of the Mn moments is responsible for this effect.
- Publication:
-
Physical Review B
- Pub Date:
- May 2001
- DOI:
- 10.1103/PhysRevB.63.184434
- Bibcode:
- 2001PhRvB..63r4434R
- Keywords:
-
- 75.30.Cr;
- 72.15.Gd;
- 71.30.+h;
- 75.60.Ej;
- Saturation moments and magnetic susceptibilities;
- Galvanomagnetic and other magnetotransport effects;
- Metal-insulator transitions and other electronic transitions;
- Magnetization curves hysteresis Barkhausen and related effects