Zero-Field Manganese Nuclear Magnetic Resonance in Antiferromagnetic Manganese Fluoride

摘要: The zero-field NMR of ${\mathrm{Mn}}^{55}$ has been observed directly in the antiferromagnetic state Mn${\mathrm{F}}_{2}$. A single resonance, with linewidth $\ensuremath{\Delta}{\ensuremath{\nu}}^{55}\ensuremath{\simeq}1.3$ Mc/sec, was frequency range 650-675 Mc/sec and temperature 1.3-20.5\ifmmode^\circ\else\textdegree\fi{}K. extrapolated at 0\ifmmode^\circ\else\textdegree\fi{}K is found to be ${{\ensuremath{\nu}}_{0}}^{55}=671.4\ifmmode\pm\else\textpm\fi{}0.2$ Mc/sec. Combining together dipolar field ${H}_{\mathrm{dip}}=+5.770$ kOe hyperfine coupling constant ${A}^{55}=\ensuremath{-}(90.78\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ ${\mathrm{cm}}^{\ensuremath{-}1}$, measured for ${\mathrm{Mn}}^{2+}$ Zn${\mathrm{F}}_{2}$, gives a value zero-point spin deviation $1\ensuremath{-}\frac{〈S〉}{S}=(0.43\ifmmode\pm\else\textpm\fi{}0.34)%$. This compared predicted by spin-wave theory 2.37%. dependence agrees, within experimental error, temperture ${\mathrm{F}}^{19}$ Upper lower limits 1300 kc/sec 600 are placed on contribution Mn${\mathrm{F}}_{2}$ Suhl-Nakamura interaction.