Аннотация:Modern technology companies strive to improve devices - make them compact and energy-saving. For this it is necessary that the same element in the microcircuit simultaneously performs several functions. Magnetic semiconductors, in particular, manganites with a perovskite-like structure (R1-xAxMnO3, where R = La, Pr, Nd, Sm, etc., A = Sr2+, Ca2+, Ba2+ etc.) can claim this role. Manganites are characterized by a strong interconnection between the crystal lattice with electronic and magnetic subsystems, which leads to a number of unusual properties. In the temperature region of the magnetic phase transition giant values of magnetoresistance, magnetostriction, thermopower, magnetothermopower, magnetocaloric effect etc. are observed. The aim of this work is to establish the relationship between the structure and physical properties (resistance, magnetoresistance, thermopower and magnetothermopower) of the Pr0.65(Ca0.8Sr0.2)0.35MnO3 monocrystal. The electrical resistance and magnetoresistance, thermopower and magnetothermopower of the studied monocrystal were measured in the temperature range 90–300 K in magnetic fields of 1–15 kOe. The temperature and field dependences of these parameters are analyzed. It was found that the resistivity of the sample increases with decreasing temperature. Starting from a temperature of 120 K it sharply increases and at 104 K it passes through a maximum. Influence of a magnetic field leads to a decrease in resistivity. Negative magnetoresistance passes through a maximum at 104 K and reaches a value of 45% in a magnetic field of 15 kOe. We emphasize that the maximum of resistance and magnetoresistance are observed at the temperature exceeding the temperature of the magnetic phase transition (85 K) by about 20 K. When approaching the temperature of the magnetic phase transition from the high temperature side, a sharp increase in the thermopower was found. So, at the temperature of 98 K, the thermopower reaches 250 μV/K, which is comparable with the thermopower of widely used thermoelectric materials based on bismuth telluride. When a magnetic field is applied, the thermopower decreases, and the magnetothermopower reaches 50% in a magnetic field of 15 kOe at 98 K. A feature of this compound is its magnetic and structural heterogeneity. The charge-ordered antiferromagnetic phase coexists with the ferromagnetic phase, and these phases have a different crystalline structure. It is assumed that the detected large values of thermopower and magnetothermopower are caused by these inhomogeneities.
