Kinetic arrest of the first-order R3̄c to Pbnm phase transition in supercooled La xMnO 3+ (x=1 and 0.9)

Aga Shahee, Dhirendra Kumar, Chandra Shekhar, N. P. Lalla

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11 Scopus citations

Abstract

We report the occurrence of kinetic arrest of the first-order phase transition from R3̄c to Pbnm in supercooled La xMnO 3±δ (x = 1 and 0.9, i.e. δ > 0:125). Structural studies have been done, employing low temperature transmission electron microscopy (LT-TEM) and low temperature x-ray diffraction (LT-XRD) techniques. No phase transformation was observed even in La xMnO 3±δ aged for ∼12 h at 98 K. The evidence of the occurrence of kinetic arrest was realized at low temperatures through in situ electron beam triggered nucleation and perpetual devitrification of the R3̄c phase into a Pbnm phase. It was clearly evidenced that the R3̄c structure of La xMnO 3±δ, below its ferromagnetic transition temperature, is metastable and prone to be transformed to a Pbnm orthorhombic structure following initiation by an electron beam trigger. The electron beam transformed Pbnm phase was found to transform back to the R3̄c phase through a first-order phase transition occurring close to the ferromagnetic to paramagnetic transition (Tc) during heating. The glass-like kinetics of the arrested R3̄c phase has been investigated through resistance relaxation measurements, showing a decreasing logarithmic rate of decay of the arrested R3̄c phase towards the stable Pbnm phase with decreasing temperature, down to 5 K. On the basis of the correlations observed in the resistance-versus-temperature, magnetization-versus-temperature, magnetization-versus-field, resistance relaxation and LT-XRD measurements, the occurrence of kinetic arrest has been attributed to the suppression of Jahn-Teller distortion by double exchange across the insulator-metal transition.

Original languageEnglish
Article number225405
JournalJournal of Physics Condensed Matter
Volume24
Issue number22
DOIs
StatePublished - 6 Jun 2012
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science (all)
  • Condensed Matter Physics

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