We report on the nuclear magnetic resonance (NMR) study of "colossal magnetoresistive" manganites La_1-xSr_xMnO3. The temperature measurement of zero field ⁵⁵Mn and ¹³⁹La spin-echo spectra were carried out on samples with doping x=0.125 and 0.15. Previous works on these compounds suggest that the ground state of both compounds is a ferromagnetic conductor below T_C and orbitally ordered ferromagnetic insulator below T_OO < T_C. Neutron diffraction, magnetization, resistivity and linear thermal expansion measurements on our polycrystalline samples indicate T_C around 205 K and 240 K, for x=0.125 and x=0.15, respectively. The temperature of orbital ordering, T_OO, is 150 K and 180 K for x=0.125 and x=0.15, respectively. The ⁵⁵Mn spectra of both compounds exhibits Mn³⁺ and Mn⁴⁺ as well as double exchange (DE) lines with different relative intensities. The DE line corresponds to ferromagnetic metallic clusters (FMM) and the Mn³⁺ and Mn⁴⁺ lines are due to charge localised (CL) ferromagnetic insulating (FMI) regions. The DE line for x=0.125 is observed up to temperatures around or slightly above bulk T_C, revealing the presence of long lived FMM clusters. The intensity of the Mn⁴⁺ line decreases strongly with increasing temperature and the signal is not observed above 150 K due to the melting of FMI regions. The ¹³⁹La spectra of both compounds at 4.2K exhibit two lines, which are attributed to FMM and FMI regions and the ratio of their intensities is similar to that of the respective FMM and FMI signals in the ⁵⁵Mn spectra. This ratio shows that there are fewer FMM clusters in x=0.125 than in x=0.15. Measurements on the ⁵⁵Mn DE line at 4.2 K, for different pulse spacing, shows no effect of the Suhl-Nakamura interaction for x=0.125, in contrast to x=0.15. This feature indicates that the FMM clusters for x=0.125 are of nanometer size, whereas for x=0.15 they are much larger.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/949 must be provided.

1. Valence band of tungsten compounds probed using 2p5d RIXS
2. A study of surface oxidised Fe particles with Mössbauer spectroscopy
3. A XAS study of surface oxidised Fe particles
4. Magnetite-based nanoparticles as contrast agents for MRI
5. Structural, magnetic and electronic properties of surface oxidised Fe nanoparticles
6. Transport properties in the pseudobinary Er₅Si₄ compound
7. NMR study of (Sr,Ba,La)₂Fe_1+xMo_1-xO₆ double perovskites
8. A ⁵⁵Mn NMR study of La_0.33Nd_0.33Ca_0.34MnO₃ with ¹⁶O and ¹⁸O
9. XANES and X-MCD study of Nd₂TM₁₇A_x (TM=Fe, Co; A=N,H) compounds