• Georgalas, C.; Samartzis, A.; Biniskos, N.; Syskakis, E.: Effects of Cr-doping on the Jahn-Teller, the orthorhombic to rhombohedral, and the magnetic transitions in LaMn1-xCrxO3 compounds. Physica B 586 (2020), p. 412101/1-8

10.1016/j.physb.2020.412101

Abstract:
We report on the electrical resistivity, the specific heat, and differential thermal analysis of LaMn1-xCrxO3 (x = 0.00–0.35) polycrystalline compounds at T > 300 K, as well as on their magnetic properties in the temperature range from 80 K to 280 K. The transport and the thermal results show that the isovalent substitution of Mn3+ by Cr3+ decreases the cooperative Jahn-Teller distortion and consequently affects orbital ordering in the whole concentration range. It is found that Cr drastically reduces the entropy change associated to the Jahn-Teller transition to negligible values for x ≥ 0.20. The orthorhombic to rhombohedral transition is also displaced to lower temperatures by Cr-doping, however exhibiting non-zero associated enthalpy changes for all x. A ferromagnetic contribution develops in orbitally disordered alloys with x ≥ 0.20. The paramagnetic to ferromagnetic transition temperatures show a similar variation upon increasing x as for the LaMn1-xGaxO3 system, implying a common origin for the ferromagnetic interaction in both systems.