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Huge thermal hysteresis loop and a hidden stable phase in a charge-transfer phase transition of Rb 0.64 Mn [ Fe ( CN ) 6 ] 0.88 ∙ 1.7 <…

2006; American Physical Society; Volume: 73; Issue: 17 Linguagem: Inglês

10.1103/physrevb.73.172415

1550-235X

Hiroko Tokoro, Seiji Miyashita, Kazuhito Hashimoto, Shin‐ichi Ohkoshi,

Electron Spin Resonance Studies

The charge-transfer phase transition in ${\mathrm{Rb}}_{0.64}^{\mathrm{I}}{\mathrm{Mn}}^{\mathrm{II}}[{\mathrm{Fe}}^{\mathrm{III}}(\mathrm{CN}{)}_{6}{]}_{0.88}∙1.7{\mathrm{H}}_{2}\mathrm{O}$ exhibits a surprisingly large thermal hysteresis loop of $138\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, i.e., the phase transition temperatures are $165\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ $(={T}_{1∕2\ensuremath{\downarrow}})$ and $303\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ $(={T}_{1∕2\ensuremath{\uparrow}})$. Switching between ${\mathrm{Fe}}^{\mathrm{III}}\text{\ensuremath{-}}\mathrm{CN}\text{\ensuremath{-}}{\mathrm{Mn}}^{\mathrm{II}}$ and ${\mathrm{Fe}}^{\mathrm{II}}\text{\ensuremath{-}}\mathrm{CN}\text{\ensuremath{-}}{\mathrm{Mn}}^{\mathrm{III}}$ causes this phase transition. When the sample is rapidly cooled, a hidden stable phase of ${\mathrm{Fe}}^{\mathrm{III}}\text{\ensuremath{-}}\mathrm{CN}\text{\ensuremath{-}}{\mathrm{Mn}}^{\mathrm{II}}$ is observed, which relaxes to ${\mathrm{Fe}}^{\mathrm{II}}\text{\ensuremath{-}}\mathrm{CN}\text{\ensuremath{-}}{\mathrm{Mn}}^{\mathrm{III}}$ at $114\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ with a warming. A thermodynamical model under thermal equilibrium condition demonstrates this large thermal hysteresis loop and proves the existence of the hidden stable phase.