arXiv subjects

R. T. Giles

Publications and source records attributed to R. T. Giles.

3 recordsLinked to original sources

arXiv1998

D-wave Bose-Einstein condensation and the London penetration depth in superconducting cuprates

We show that bipolaron formation leads to a d-wave Bose-Einstein condensate in cuprates. It is the bipolaron energy dispersion rather than a particular pairing interaction which is responsible for the d-wave symmetry. The unusual low-temperature dependence of the magnetic field penetration depth in cuprates is explained by the localisation of bosons in the random potential. The temperature dependence of the penetration depth is linear with positive or negative slope depending on the random field profile.

cond-mat.supr-con↗

arXiv1997

Low temperature thermodynamics of charged bosons in a random potential and the specific heat of La_{2-x}Sr_{x}CuO_{4} below Tc

We propose a simple analytical form of the partition function for charged bosons localised in a random potential and derive the consequent thermodynamics below the superfluid transition temperature. In the low temperature limit, the specific heat, C, depends on the localisation length exponent nu: C is linear for nu<1, but for nu>1 we find C proportional to T^{1/nu}. This unusual sub-linear temperature dependence of the specific heat has recently been observed in La_{2-x}Sr_{x}CuO_{4} below Tc.

cond-mat.supr-con↗

arXiv1997

Parastatistics of charged bosons partly localised by impurities

Coulomb repulsion is taken into account to derive the thermodynamics of charged bosons in a random external potential. A simple analytical form of the partition function is proposed for the case of non-overlapping localised states (i.e. a small amount of disorder). The density of localised bosons and the specific heat show a peculiar non-uniform temperature dependence below the Bose-Einstein condensation temperature. The superfluid - Bose-glass phase diagram is discussed. A new phase is predicted which is a Bose-glass at T=0 but a superfluid at finite T.

cond-mat.supr-con↗