We develop a simple calculational scheme for thermodynamic properties of superconducting states under magnetic fields. A combination of an approximate analytic solution with a free energy functional in the quasiclassical theory provides a wide use formalism for spatial-averaged thermodynamic properties, and requires a little numerical computation. The theory covers multiband superconductors with various set of singlet and unitary triplet pairings in the presence of an impurity scattering. We demonstrate the application to s-wave, dx2-y2-wave and two-band s-wave pairings, and discuss the validity of the theory comparing with previous numerical studies. Using the formalism, we examine the influence of modulation of gap functions and anisotropy of Fermi velocity to upper critical field and specific heat under the oriented magnetic fields. The validity of the Doppler shift method and its range of applicability in the temperature-field phase diagram is discussed. This result gives a concrete theoretical ground for recent development of the angle-resolved experiments under the oriented magnetic fields.
|Title of host publication||Superconductivity Systems, Properties and Theories|
|Publisher||Nova Science Publishers, Inc.|
|Number of pages||30|
|Publication status||Published - 1 Dec 2011|