55Mn NMR study of La1.2Sr1.8−xCaxMn2O7 (x=0, 0.1, 0.2)

Abstract We performed 55 Mn spin-echo NMR measurements at 4.2 K on single crystals of the double-layered compound La 1.2 Sr 1.8− x Ca x Mn 2 O 7 ( x =0, 0.1, 0.2). In an external magnetic field of 1.75 T, all the spectra remain broad, with several distinct resonance lines. The observed resonance lines arising from Mn 4+ and Mn 3+ , in addition to that from the metallic phase, strongly suggest an electronic phase separation in La 1.2 Sr 1.8− x Ca x Mn 2 O 7 ( x =0, 0.1, 0.2).