Eur. Phys. J. B 35, 295-300 (2003)
https://doi.org/10.1140/epjb/e2003-00280-6

Nonlinear properties of ferromagnetic La_1-xCa_xMnO₃ single crystals

¹ Department of Physics, Ben Gurion University of the Negev, PO Box 653, 84105 Beer Sheva, Israel
² Laboratoire des Solides Irradiés, École Polytechnique, 91128 Palaiseau, France
³ Moscow State Steel and Alloys Institute, 119049 Moscow, Russia

Corresponding author: ^a jung@bgumail.bgu.ac.il

Received: 12 May 2003
Published online: 15 October 2003

Abstract

The resistive and magnetic properties of La_1-xCa_xMnO₃ single crystals are investigated. In particular, properties of close-to-critically doped crystals with x=0.22 are confronted with those of underdoped crystals with x=0.18 and x=0.2 and optimally doped crystals with x=0.3. A systematic investigation of nonlinear transport shows that the critically doped crystal does not simply constitute an intermediate case between strongly nonlinear underdoped and linear, optimally doped one. The observed low-temperature resistivity increase can be interpreted in terms of orbital ordering or as a manifestation of an intrinsic tunnelling mechanism. The transport measurements have been completed by magneto-optic investigations which suggest that the low temperature resistivity of the underdoped x=0.18 compound is dominated by tunnelling through intrinsic barriers associated with twin domains, while phase separation dominates in the critically doped x=0.22 compound.