Journal of Magnetism and Magnetic Materials 290–291 (2005) 910–913 Electron magnetic resonance (EMR) study of electron–hole asymmetry in La 1x Ca x MnO 3 manganites (x ¼ 0.2,0.8) A.I. Shames a , E. Rozenberg a,Ã , M. Auslender b , G. Gorodetsky a , C. Martin c , A. Maignan c , Ya.M. Mukovskii d a Department of Physics, Faculty of Natural Science, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel b Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel c Laboratoire CRISMAT, UMR 6508, ISMRA, 14050 Caen Cedex, France d Moscow Steel and Alloys Institute, Leninskii prosp. 4, Moscow 117936, Russian Federation Available online 8 December 2004 Abstract X-band EMR measurements on powdered samples of single-crystalline La 0.8 Ca 0.2 MnO 3 and polycrystalline La 0.2 Ca 0.8 MnO 3 manganites were carried out at 120pTp500K aiming to study the effect of the electron–hole doping asymmetry in La 1x Ca x MnO 3 system. In the paramagnetic (PM) state both compounds differ in the nature of short- range magnetic orderings observed—clusters of double-exchange coupled Mn 3+ –Mn 4+ ions and magneto-impurity- like clusters in the La 0.8 Ca 0.2 MnO 3 and La 0.2 Ca 0.8 MnO 3 compounds, respectively. Ferromagnetic ground state of La 0.8 Ca 0.2 MnO 3 is characterized by the coexistence of orbitally ordered Mn 3+ subsystem and Mn 4+ with band-like carriers one, which are responsible for the multiline EMR spectra. Charge-ordered antiferromagnetic ground state of La 0.2 Ca 0.8 MnO 3 causesasharpdecreaseinintensityandthenvanishingoftheEMRsignalobservedinthePMregion. r 2004 Elsevier B.V. All rights reserved. PACS: 75.30.Kz; 76.50.Dd; 76.50.+g Keywords: Ferromagnetic and electron paramagnetic resonance; Electron and hole-doped manganites The important feature of the phase diagram of La 1x Ca x MnO 3 (LCMO) manganite system is its evident asymmetry between the hole- (xo0:5) and electron-doped (x40:5) regions [1]. Namely, the hole- doped region reveals ferromagnetic metallic-like (FMM) ground state for 0:22pxo0:5; while the electron-doped one—mainly charge-ordered antiferromagnetic insulat- ing (CO AFMI) ground state [1,2]. It is commonly accepted now [3–5] that the coexistence of FMM and FM insulating-like (FMI) phases is typically observed fortheconcentrationinterval0:1pxo0:22: Ontheother hand, recent neutron diffraction and magnetization measurements [6,7] established that, with x decreasing from 1.0 to 0.8, a gradual change of AFMI ground state from G to C-type AFM (throughout the intermediate cluster glass FM-like state for x  0:9) takes place in LCMO. The main goal of the present study is EMR probing of basically different magnetic states in symme- trical (regarding its Ca content) La 0.8 Ca 0.2 MnO 3 and La 0.2 Ca 0.8 MnO 3 compounds (marked further as Ca 0.2 and Ca 0.8 )—representatives of the hole- and electron- dopedregionsoftheLCMOphasediagram,respectively. EMR spectra were recorded using Bruker EMX-220 X-band (n ¼ 9:4GHz) spectrometer within the ARTICLE IN PRESS www.elsevier.com/locate/jmmm 0304-8853/$-see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2004.11.287 Ã Corresponding author. Tel.: 97286472456; fax: +97286472903. E-mail address: evgenyr@bgumail.bgu.ac.il (E. Rozenberg).