Common energy scale for magnetism and superconductivity in underdoped cuprates:: A muon spin resonance investigation of (CaxLa1-x) (Ba1.75-xLa0.15x)Cu3Oy -: art. no. 137003

We characterize the spontaneous magnetic field, and determine the associated temperature T-g, in the superconducting state of (CaxLa1-x) (Ba1.75-xLa0.25+x) Cu3Oy using zero and longitudinal field muon spin resonance measurements for various values of x and y. Our major findings are (i) T-g and T-c are controlled by the same energy scale, (ii) the phase separation between hole poor and hole rich regions is a microscopic one, and (iii) spontaneous magnetic fields appear gradually with no moment size evolution.