MRSej, Vol. 6, No.1, pp.191-197, 2004

MICROSCOPIC PHASE SEPARATION AND TWO TYPES OF QUASIPARTICLES
IN LIGHTLY DOPED La2-xSrxCuO4
OBSERVED BY ELECTRON PARAMAGNETIC RESONANCE

A. Shengelaya1, M. Bruun1, K.A. Müller1, A. Safina2, K. Conder3

1 Physik-Institut der Universität Zürich, Zürich CH-8057, Switzerland

2 Kazan State University, Kazan , 420008, Russia

3 ETH Zürich and PSI, CH-5232 Villigen PSI, Switzerland

In the low doping range of x from 0.01 to 0.06 in La2-xSrxCuO4 , we observed two electron paramagnetic resonance (EPR) signals: a narrow and a broad one. The narrow line is ascribed to metallic regions in the material, and its intensity increases exponentially upon cooling below  ~  150 K. The activation energy deduced $\Delta$  = 460(50) K is nearly the same as that found in the doped superconducting regime by Raman and neutron scattering. Obtained results provide evidence of the microscopic phase separation and two type of quasiparticles in lightly doped La2-xSrxCuO4.

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