First-Order Vortex Lattice Melting and Magnetization of YBa$_2$Cu$_3$O$_{7-δ}

R. Sasik; D. Stroud

doi:10.1103/PhysRevLett.75.2582

paper

First-Order Vortex Lattice Melting and Magnetization of YBa $_{2}$ Cu $_{3}$ O$_{7-δ}

arXiv:supr-con/9506002 · doi:10.1103/PhysRevLett.75.2582

Abstract

We present the first non-mean-field calculation of the magnetization $M (T)$ of YBa $_{2}$ Cu $_{3}$ O $_{7 - δ}$ both above and below the flux-lattice melting temperature $T_{m} (H)$ . The results are in good agreement with experiment as a function of transverse applied field $H$ . The effects of fluctuations in both order parameter $ψ (r)$ and magnetic induction $B$ are included in the Ginzburg-Landau free energy functional: $ψ (r)$ fluctuates within the lowest Landau level in each layer, while $B$ fluctuates uniformly according to the appropriate Boltzmann factor. The second derivative $(\partial^{2} M / \partial T^{2})_{H}$ is predicted to be negative throughout the vortex liquid state and positive in the solid state. The discontinuities in entropy and magnetization at melting are calculated to be $\sim 0.034 k_{B}$ per flux line per layer and $\sim 0.0014$ ~emu~cm $^{- 3}$ at a field of 50 kOe.

11 pages, 4 PostScript figures in one uuencoded file

First-Order Vortex Lattice Melting and Magnetization of YBa2​Cu3​O$_{7-δ}

Abstract

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First-Order Vortex Lattice Melting and Magnetization of YBa $_{2}$ Cu $_{3}$ O$_{7-δ}