Multiphase magnetic state of Ca1 ? x La x MnO3 ? δ single crystals ( x = 0.03, 0.05, 0.07) containing oxygen vacancies

Magnetic properties (magnetization, dynamic and static susceptibility) and transport properties (resistance and magnetoresistance) have been studied in a temperature range of 2–600 K in magnetic fields to 90 kOe for single crystals of Ca_{1 − x} La _x MnO_{3 − δ} with a weak electron doping (x ≤ 0.07) grown in argon and oxygen atmospheres. The magnetic state of Ca_{1 − x} La _x MnO_{3 − δ} single crystals is multiphase. Below T = T _N(G) ∼ 110 K, in all the crystals there coexists an AFM G phase with an FM contribution and an AFM C phase. In crystals with x = 0.07, a transition from the paramagnetic phase into the AFM C phase occurs in part of their volume below T ∼ 130–150 K. In crystals with x = 0.05 annealed in oxygen, an anomaly of paramagnetic susceptibility is observed near T ^* ∼ 270 K, which is related to the formation of FM clusters near defects. At x = 0.05 and 0.07, AFM correlations are retained in the paramagnetic state (to 600 K). The differences in the magnetic and transport properties of single crystals grown in argon and oxygen are explained by the various content of oxygen vacancies and by their possible ordering. Original Russian Text ? N.N. Loshkareva, A.V. Korolev, T.I. Arbuzova, N.I. Solin, A.M. Balbashov, N.V. Kostromitina, 2007, published in Fizika Metallov i Metallovedenie, 2007, Vol. 103, No. 3, pp. 261–270.