Effect of Alloying with Ca in LaMnO_{3} System Studied by KKR-CPA Method and Giant Magnetoresistance

• Authors: J. Tobola , S. Kaprzyk , J. Pierre
• Languages of publication: EN

Abstracts

EN

La_{1-x} Ca_{x}MnO_{3} perovskites show semiconducting properties in the paramagnetic range. The gap is reduced near x=0.33, where ferromagnetic ordering is observed. The ferromagnetic ordering then induces a semiconductor-metal transition, and gives rise to a giant magnetoresistance effect. The ground state electronic structure calculations were done with KKR-CPA method for hypothetical cubic and ferromagnetic LaMnO_{3} and CaMnO_{3} compounds, as well as for disordered La_{1-x}Ca_{x}MnO_{3} (x=0.33, 0.4, 0.5) alloys with real crystal data. As a result, we get a magnetic moment per formula 4.00μ_{B} and 3.00μ_{B} and half-metallic behaviour for end-compounds, respectively. In the ferromagnetic region a linear decrease in the magnetic moment of La_{1-x}Ca_{x}MnO_{3} is observed, together with the decrease in the gap width for spin-down carriers, if doping Ca in La_{1-x}Ca_{x}MnO_{3}. A simple model is developed, which describes magnetic and transport properties as resulting from an exchange-induced band-crossing semiconductor-metal transition, as for instance in EuO.

Keywords

EN

71.20.-b; 71.20.Lp

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 1997
• Volume: 92
• Issue: 2
• Pages: 461-464

Dates

published

1997-08

Contributors

author

J. Tobola

• Faculty of Physics and Nuclear Techniques, AGH, Al. Mickiewicza 30, 30-059 Kraków, Poland

author

S. Kaprzyk

• Faculty of Physics and Nuclear Techniques, AGH, Al. Mickiewicza 30, 30-059 Kraków, Poland

author

J. Pierre

• Laboratoire de Magnetisme, L. Néel, CNRS, BP-166X Grenoble, France