Phys. Rev. B 71, 014430 (2005) [4 pages]Nuclear magnetic resonance study of insulator-metal transitions in (Pr,Ca)MnO3Received 17 April 2004; revised 3 September 2004; published 21 January 2005 An NMR study of polycrystalline Pr0.5Ca0.5Mn1−xGaxO3 (x=0 and 0.03) and Pr0.67Ca0.33MnO3 at 3 K is presented. Zero-field spin-echo spectra of the Ga-doped compound consist of an overlapping 69,71Ga signal at 74 MHz (hyperfine field of 5.3 T) and a 55Mn double-exchange (DE) line at 375 MHz (35.5 T). Measurements in an applied field show a steplike increase in the DE line intensity, which corresponds to an increase of the amount of the ferromagnetic metallic phase. This coincides with a steplike feature in the bulk magnetization measurements. The effect is similar to that in the previous field-dependent 55Mn NMR measurements of Pr0.67Ca0.33MnO3. The insulator - metal transition for Pr0.67Ca0.33MnO3, at ambient pressure, occurs at fields greater than 5 T; however, at 1.1 GPa, the DE line corresponding to the ferromagnetic metallic phase is already present at zero field. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.71.014430
DOI:
10.1103/PhysRevB.71.014430
PACS:
76.60.−k, 75.47.Lx, 75.50.−y
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