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<img src='content_image/327794.jpg'>

Texture enhances B$_{ρ}$$_{=0}$ (compared to the prediction of Equ. 3 for untextured MgB$_{2}$), when the field is oriented parallel to the tape ( B ‖ ρ $_{=0}$, top panel in Fig. 1), but reduces B$_{ρ}$$_{=0}$ in perpendicular orientation ( B ⊥ ρ $_{=0}$, middle panel) leading to an anisotropy of B$_{ρ}$$_{=0}$ , γ$_{ρ}$$_{=0}$ := B ‖ ρ $_{=0}$/B ⊥ ρ =0 (bottom panel). The intrinsic anisotropy is obtained at α$_{t}$ = 0 ◦ (perfect texture), the anisotropy is very small at α$_{t}$ = 180 ◦ (1.02, 1.03, and 1.04 for γ = 3, 4, and 5, respectively). 

The upper critical field is less sensitive to texture than B$_{ρ}$$_{=0}$ , as demonstrated for γ = 4 in Fig. 2. The data roughly correspond to a 90% resistive criterion, since a fraction of 2.5% superconducting grains was assumed for the calculations. If, say, 25% superconducting grains were needed for zero resistivity ( p$_{c}$ = 0 . 25), around 2.5% should be enough to lower the resistivity by 10%. This definition (2.5% superconducting grains) will be used for the (angular dependent) upper critical field, B$_{c2}$ , in the following. (Henceforth B$_{c2}$ ( θ$_{t}$ ) always denotes this macroscopic upper critical and not the intrinsic B$_{c2}$ ( θ ) (Equ. 2) within the grains.) The upper critical field is nearly independent of texture, if the field is applied parallel to the tape. This is why the onset of the transition always corresponds to B ab c2 in untextured materials. A significant anisotropy of the upper critical field is observed only for α$_{t}$ below about 45 $^{◦}$. The anisotropy of the upper critical field is only 1.4, while γ$_{ρ}$$_{=0}$ is 2.4 at α$_{t}$ = 30 $^{◦}$. 

The upper critical field and its anisotropy are much more sensitive to the chosen criterion than B$_{ρ}$$_{=0}$ and γ$_{ρ}$$_{=0}$ . Therefore, and because of the field and temperature dependence of the J$_{c}$ -anisotropy (see below), γ$_{ρ}$$_{=0}$ is the most useful parameter for the quantification of the 

