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Free energy and torque for superconductors with different anisotropies of H_{c2} and lambda

V. G. Kogan
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Abstract

The free energy is evaluated for a uniaxial superconductor with the anisotropy of the upper critical field, gamma_H = H_{c2,ab}/H_{c2,c}, different from the anisotropy of the penetration depth gamma_{lambda} = lambda_c/lambda_{ab}. With increasing difference between gamma_H and gamma_{lambda}, the equilibrium orientation of the crystal relative to the applied field may shift from theta = pi/2 (theta is the angle between the field and the c axis) to lower angles and reach theta = 0 for large enough gamma_H. These effects are expected to take place in MgB_2.

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V. G. Kogan. 2002-07-29. Free energy and torque for superconductors with different anisotropies of H_{c2} and lambda. https://doi.org/10.1103/physrevlett.89.237005

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