Papavassiliou G, Pissas M, Belesi M, Fardis M, Dolinsek J, Dimitropoulos C, Ansermet JP. Orbital domain state and finite size scaling in ferromagnetic insulating manganites.
Phys Rev Lett 2003;
91:147205. [PMID:
14611553 DOI:
10.1103/physrevlett.91.147205]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2002] [Indexed: 05/24/2023]
Abstract
55Mn and 139La NMR measurements on a high quality single crystal of ferromagnetic (FM) La0.80Ca0.20MnO3 demonstrate the formation of localized Mn(3+,4+) states below 70 K, accompanied by a strong cooling-rate dependent increase of certain FM neutron Bragg peaks. (55,139)(1/T(1)) spin-lattice and (139)(1/T(2)) spin-spin relaxation rates are strongly enhanced on approaching this temperature from below, signaling a genuine phase transition at T(tr) approximately 70 K. The disappearance of the FM metallic signal by applying a weak external magnetic field, the different NMR radio-frequency enhancement of the FM metallic and insulating states, and the observed finite size scaling of T(tr) with Ca (hole) doping, as observed in powder La(1-x)CaxMnO3 samples, are suggestive of freezing into an inhomogeneous FM insulating and orbitally ordered state embodying "metallic" hole-rich walls.
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