Issue
EPL
Volume 80, Number 3, November 2007
Article Number 37001
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/80/37001
Published online 24 September 2007
EPL, 80 (2007) 37001
DOI: 10.1209/0295-5075/80/37001

Coexistence of long-ranged charge and orbital order and spin-glass state in single-layered manganites with weak quenched disorder

R. Mathieu1, J. P. He1, X. Z. Yu1, Y. Kaneko1, 2, M. Uchida1, Y. S. Lee1, T. Arima1, 3, A. Asamitsu1, 4 and Y. Tokura1, 2, 5, 6

1  Spin Superstructure Project (ERATO-SSS), JST, AIST Central 4 - Tsukuba 305-8562, Japan
2  ERATO Multiferroics Project, JST, c/o Department of Applied Physics, University of Tokyo - Tokyo 113-8656, Japan
3  Institute of Multidisciplinary Research for Advanced Materials, Tohoku University - Sendai 980-8577, Japan
4  Cryogenic Research Center (CRC), University of Tokyo - Bunkyo-ku, Tokyo 113-0032, Japan
5  Correlated Electron Research Center (CERC), AIST Central 4 - Tsukuba 305-8562, Japan
6  Department of Applied Physics, University of Tokyo - Tokyo 113-8656, Japan

rmathieu@kth.se

received 9 April 2007; accepted in final form 3 September 2007; published November 2007
published online 24 September 2007

Abstract
The relationship between orbital and spin degrees of freedom in the single crystals of the hole-doped Pr1-xCa1+xMnO4, 0.3 $ \leq$ x $ \leq$ 0.7 has been investigated by means of ac-magnetometry and charge transport. We show that in an intermediate underdoped region, with 0.35 $ \leq$ x < 0.5, the "orbital-master spin-slave" relationship commonly observed in half-doped manganites does not take place. The long-ranged charge-orbital order is not accompanied by an antiferromagnetic transition at low temperatures, but by a frustrated short-ranged magnetic state bringing forth a spin-glass phase. We discuss in detail the nature and origin of this true spin-glass state, which, as in the half-doped manganites with large quenched disorder, is not related to the macroscopic phase separation observed in crystals with minor defects or impurities.

PACS
71.27.+a - Strongly correlated electron systems; heavy fermions.
75.47.-m - Magnetotransport phenomena; materials for magnetotransport.
75.50.Lk - Spin glasses and other random magnets.

© Europhysics Letters Association 2007