Reply to the comment of Chudnovsky & Garanin on ” Spin re - laxation in Mn 12 - acetate ”
نویسنده
چکیده
Angular momentum conservation is a physical law that must be obeyed in any closed system. However, it is well known from standard textbooks that in the case of interactions with phonons a part of the total momentum and of the total angular momentum can be absorbed by the whole crystal and is then no longer considered (cf. e.g. the Mössbauer effect[1] and the Umklapp process[2]). Therefore, there is no such general reason why the spin-phonon couplings g 1 (ǫ xx − ǫ yy) ⊗ (S 2 x − S 2 y) + 1 2 g 2 ǫ xy ⊗ {S x , S y } (1) must vanish in the spin-phonon Hamiltonian H sp (see Eq. (6) in Ref. [7]) due to angular momentum conservation as incorrectly claimed in Ref. [3]. Both terms in Eq. (1) were used e.g. in Refs. [4], [5], [6], and [7] to describe phonon-assisted tunneling in Mn 12. Furthermore, such terms were derived in Refs. [8] and [9] many years ago by means of perturbation theory: These authors combined two spin-orbit interactions H SO = λL · S with one orbit-lattice interaction H OL , which yields a third-order term of the form[8] j,k
منابع مشابه
Experimental evidence of the dependence of spin tun - nelling on the concentration of dislocations in Mn 12 crys - tals
– We present experimental results on resonant spin tunnelling in a single crystal of Mn12-2Cl benzoate with different concentration of dislocations. The time evolution of the magnetisation follows the stretched exponential, M (t) ∝ exp[−(t/τ) β ] over a few time decades. The values of τ and β deduced from experiment have been used to determine the concentration of dislocations before and after ...
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Chudnovsky and Garanin have attacked harshly our paper [1] in a comment in arXiv:cond-mat [2]. They write in their comment that " all formulas of Ref. [1] are incorrect ". They question " how can ∆ be the magnetic dipole matrix element and the tunneling splitting at the same time? ". These two ∆ are obviously different and we write it explicitlely in the text: • The first ∆ appears in the expre...
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– We compute the width and shape of the EPR and tunneling resonances due to dislocations in Mn-12 acetate crystals. Uncorrelated dislocations produce the Gaussian shape of resonances while dislocations bound in pairs produce the Lorentzian shape. We stress that the uniaxial spin Hamiltonian together with crystal defects can explain the totality of experimental data on Mn-12. The discovery of re...
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تاریخ انتشار 2000