Magnetic and transport properties of polycrystalline La1-x Cax Mn O3 (x=0.8,0.9) perovskites were investigated in the temperature range 4.2-300 K, magnetic field up to 16 kOe and under hydrostatic pressures up to 12 kbar. The La0.1 Ca0.9 Mn O3 compound exhibits a heterogeneous spin configuration in its ground state [G -type antiferromagnetic (AFM) phase with local ferromagnetic (FM) regions and C -type AFM]. The x=0.8 compound is mostly an orbital ordered C -type AFM. In the case of La0.1 Ca0.9 Mn O3, an applied pressure slightly increases the magnetic transition temperature and significantly enhances the FM component. Pronounced hysteretic effects observed in La0.1 Ca0.9 Mn O3 may be attributed to the competition between the FM and AFM fractions in the G -AFM structure. On the other hand, La0.2 Ca0.8 Mn O3 is insensitive to applied pressure probably due to a robustness of orbital ordered state. Resistivity data point out that AFM ordering in La0.2 Ca0.8 Mn O3 occurs at temperatures below orbital ordering.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 14 Dec 2005|