Structural, magnetic and magneto-resistance properties of La0.88Ca0.12MnO3 single crystals

La0.88Ca0.12MnO3 single crystals of high quality have been prepared by using floating zone technique. Their composition and structure are verified using X-ray diffraction and EDAX. The temperature dependence of the resistance along ab-plane and c-axis has been measured in the temperature range 77 K to room temperature in the magnetic fields up to 8 T. The R-T data along ab-plane and c-axis shows a similar behaviour and it is the characteristics of insulating behaviour having the resistance 0.7 MΩ at 90 K and 16.1 Ω at 300 K. The insulating behaviour persists under the magnetic field up to H = 8 T. There is no resistance peak or electronic transition over the whole temperature range studied. However, there is a notable change of resistance at about 120 K, seemingly related to paramagnetic insulator to ferromagnetic insulator transition and is confirmed by magnetization measurement transition at a temperature Tc = 122 K. The sharp peak around the same temperature in the heat capacity measurement indicates the onset of long range ordering. The magnetoresistance measured at different magnetic fields shows similar kind of behaviour with some marginal change in the magnitude along ab-plane and c-axis. (author)