Field-controlled magnetic phase separation in (La0.25Pr0.75)0.7Ca0.3Mn18O3 probed by 55Mn NMR
Abstract
The influence of the 16O-18O isotope substitutions on magnetic state of perovskite-type manganite (La0.25Pr0.75)0.7Ca0.3MnO3 is studied by 55Mn NMR. Successive cycling with an isochronal exposure at different magnetic fields up to H=8T is used to study the field-induced transition from antiferromagnetic insulating (AFI) state to the ferromagnetic metal (FMM) one in the 18O-enriched sample. After exposure at H>Hcr∼ 5.3T the NMR spectrum of the 18O sample provides evidence for a magnetic phase separation (PS) into the coexisting AFI and FMM domains. Further increase of exposing field leads to a progressive growth of the FMM phase at the expense of AFI domains. Its relative fraction can be controlled by external magnetic field and the resulting magnetic structure in the PS region is discussed. Anomalous T dependence of the 55Mn nuclear spin-lattice relaxation rate is revealed in the FMM state of both 16O- and 18O-enriched samples. The possible influence of the Pr magnetic ordering at T∼40 K on the spin-lattice relaxation is considered.
- Publication:
-
Physical Review B
- Pub Date:
- May 2003
- DOI:
- 10.1103/PhysRevB.67.184410
- Bibcode:
- 2003PhRvB..67r4410G
- Keywords:
-
- 75.47.Gk;
- 75.25.+z;
- 76.60.Jx;
- Colossal magnetoresistance;
- Spin arrangements in magnetically ordered materials;
- Effects of internal magnetic fields