2016/01/07 by P. Salas, M. Fortes, M. A. Solís +2
Materials Science · Physics and Astronomy · #Boson #Brillouin zone #Condensed matter physics #Cuprate #Fermion #Iron-based superconductors research #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Superconductivity #Superconductivity in MgB2 and Alloys #cond-mat.supr-con
paper · pdf · doi:10.1016/j.physc.2016.03.002
13 pages, 6 figures
arxiv created 2016/01/07 · openalex publication_date 2016/03/14 · arxiv updated 2016/05/04 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We adapt the Boson-Fermion superconductivity model to include layered systems such as underdoped cuprate superconductors. These systems are represented by an infinite layered structure containing a mixture of paired and unpaired fermions. The former, which stand for the superconducting carriers, are considered as noninteracting zero spin composite-bosons with a linear energy-momentum dispersion relation in the CuO2 planes where superconduction is predominant, coexisting with the unpaired fermions in a pattern of stacked slabs. The inter-slab, penetrable, infinite planes are generated by a Dirac comb potential, while paired and unpaired electrons (or holes) are free to move parallel to the planes. Composite-bosons condense at a critical temperature at which they exhibit a jump in their specific heat. These two values are assumed to be equal to the superconducting critical temperature Tc and the specific heat jump reported for YBa2Cu3O6.80 to fix our model parameters namely, the plane impenetrability and the fraction of superconducting charge carriers. We then calculate the isochoric and isobaric electronic specific heats for temperatures lower than Tc of both, the composite-bosons and the unpaired fermions, which matches recent experimental curves. From the latter, we extract the linear coefficient (γn) at Tc, as well as the quadratic (αT2) term for low temperatures. We also calculate the lattice specific heat from the ARPES phonon spectrum, and add it to the electronic part, reproducing the experimental total specific heat at and below Tc within a 5 % error range, from which the cubic (ßT3) term for low temperatures is obtained. In addition, we show that this model reproduces the cuprates mass anisotropies.