The European Physical Journal B (EPJ B)

Issue		Eur. Phys. J. B Volume 14, Number 3, April 2000
Page(s)		431 - 438
DOI		10.1007/s100510051051

Eur. Phys. J. B 14, 431-438

Jahn-Teller distortion and magnetoresistance in electron doped Sr_1-xCe_xMnO₃(x = 0.1, 0.2, 0.3 and 0.4)

A. Sundaresan¹ - J.L. Tholence¹ - A. Maignan² - C. Martin² - M. Hervieu² - B. Raveau² - E. Suard³

¹ LEPES-CNRS, B.P. 166, 38042 Grenoble Cedex 09, France
² Laboratoire CRISMAT, ISMRA, 6 bd du Maréchal Juin, 14050 Caen, France
³ Institut Laue-Langevin, 38000 Grenoble, France
tholence@labs.polycnrs-gre.fr

Received 10 September 1999

Abstract
Neutron and electron diffraction, electrical transport and magnetic measurements have been carried out on a newly synthesized electron doped Sr_1-xCe_xMnO₃ ( x = 0.1, 0.2, 0.3 and 0.4) system. For x=0.1, while cooling, it undergoes a first-order metal-insulator transition at 315 K which is associated with a structural transition from cubic (Pm3m) to tetragonal (I4/mcm) due to Jahn-Teller ordering ( $T_{\mathrm} \sim 315~\mathrm{K}$ ) which stabilizes a chain like (C-type) antiferromagnetic ground state with $T_{\mathrm \sim 290~\mathrm{K}$ . The antiferromagnetic insulator state is insensitive to an applied magnetic field of 7 T. With increase of x, while the nuclear structure at room temperature for x=0.2 and 0.3 remains tetragonal, for x=0.4 it becomes orthorhombic (Imma) where the doping electrons seem to occupy mainly the d_x²-y² symmetry. Further, the JT distortion and the antiferromagnetic interactions decrease with doping and a small negative magnetoresistance appears for $x \geq 0.2$ . Magnetic measurements show that the dilution of antiferromagnetic interaction results into a spin glass like behaviour at low temperature for the samples with x=0.3 and 0.4. This behaviour is in contrast with the CMR properties of calcium based electron doped systems and hole doped manganites. The stability of C-type antiferromagnetic ordering in the electron doped system with large A-site cationic size may be responsible for the absence of double exchange ferromagnetism and CMR effect.

PACS
75.25.+z Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source X-ray scattering, etc.) - 75.30.Vn Colossal magnetoresistance - 71.30.+h Metal-insulator transitions and other electronic transitions

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Jahn-Teller distortion and magnetoresistance in electron doped Sr1-xCexMnO3(x = 0.1, 0.2, 0.3 and 0.4)

Jahn-Teller distortion and magnetoresistance in electron doped Sr_1-xCe_xMnO₃(x = 0.1, 0.2, 0.3 and 0.4)