Физика Низких Температур: Том 27, Выпуск 4 (Апрель 2001), c. 385-391    ( к оглавлению , назад )

Effect of oxygen content on magnetization and magnetoresistance properties of CMR manganites

S. V. Trukhanov, I. O. Troyanchuk, and F. P. Korshunov

Institute of Solid State and Semiconductor Physics of National Academy of Sciences of Belarus, 17 P. Brovki Str., Minsk 220072, Belarus
E-mail: troyan@ifttp.bas-net.by

V. A. Sirenko

B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Science of Ukraine 47 Lenin Ave., Kharkov 61164, Ukraine

H. Szymczak

Institute of Physics of Polish Academy of Sciences, 32/46 Al. Lotnikow Str., 02-668 Warsaw, Poland

K. Baerner

Physikalisches Institut der Universitat Goettingen, 11-15 Bunsenstr., 37073 Goettingen, Germany

Received 26 October, 2000

Аннотация

The influence of oxygen content on the magnetization and electrical resistivity of Ln0.5A0.5MnO3 (Ln=La,Pr,Nd; A=Ca,Ba) manganites with the perovskite structure is investigated. It is shown that the La0.5Ca0.5MnO3-g compound undergoes a sequence of transitions from an antiferromagnetic (g=0) to a spin-glass (g=0.17) state and then to an inhomogeneous ferromagnetic (g=0.3) state. A transition from an antiferromagnetic charge-ordered state to a ferromagnetic charge-disordered state in Nd0.5Ca0.5 MnO3-g is observed as the oxygen content is reduced to where g=0.07. The Nd0.5Ba0.5 MnO3-g compound shows an increase of the Curie point from 110 K (g=0) up to 310 K (g=0.3). In addition, a large magnetoresistance is revealed which develops below their Curie temperature despite the absence of Mn3+√Mn4+ pairs. A Zener double-exchange interaction is usually used in literature to explain the magnetic and electrical properties of hole-doped perovskite manganites. The data obtained support the mechanism of superexchange interactions between magnetic moments of the manganese ions via oxygen.

PACS:
75.30.Vn -
75.30.Cr - Saturation moments and magnetic susceptibilities