• Magnetic properties and peculiarity of magnetic states in dilute antiferromagnets Mn1−xZnxF2

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    • Keywords


      Magnetic properties; antiferromagnets

    • Abstract


      The dependence of magnetic moment and susceptibility on temperature, magnetic field and frequency of some single crystals Mn1−xZnxF2 (xxe=0.75—percolation limit) were experimentally investigated. Our experiments show that (Bazhan and Petrov 1984; Cowleyet al 1984; Villain 1984) in these crystals the nonequilibrium magnetic state of spinglass type with finite correlation length appears as temperature decreasesT<T in weak magnetic fields. This state is determined by fluctuation magnetic moments √ (wheren is the number of magnetic ions, corresponding to finite correlation length andμ the magnetic moment Mn+1).

      In the experiments in low magnetic fields and frequencies there are no peculiarities in the magnetic susceptibility temperature dependence atTTf. At temperaturesT>Tf andT<Tf magnetic susceptibility is determined by$$\chi \left( {T > T_f } \right) = \frac{{N\left\langle \mu \right\rangle ^2 }}{{3k\left( {T + \theta } \right)}} = \frac{N}{n}\frac{{\left\langle {\sqrt n \mu } \right\rangle ^2 }}{{3k\left( {T + \theta } \right)}} = \chi \left( {T< T_f } \right)$$. In strong magnetic fields and large frequencies there are peculiarities in thex(T) dependence atT=Tf. AtT<Tf and strong magnetic fieldsX(T)=x0 andT<Tf and at large frequenciesx(T)=x0+α/T.

      The dependences of magnetic susceptibility on the frequency are determined by the magnetic system relaxation. Calculations and comparison with experiments show that the relaxation of the investigated magnetic systems atT<Tf follows the relaxation lawM(t)=M(0) exp[−(t/τ)r], suggested in Palmeret al (1984) for spin-glasses relaxation taking into account the time relaxation distributionτ0....τmax in the system and its ‘hierarchically’ dynamics.

    • Author Affiliations


      A N Bazhan1 S V Petrov1

      1. Institute for Physical Problems, USSR Academy of Sciences, Moscow - 117334, USSR
    • Dates

  • Pramana – Journal of Physics | News

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