Boson localization and universality in YBa2Cu(3-x)M(x)O(7-delta)
The authors consider a two component mixture of charged fermions on neutralizing background with all sign combinations and arbitrarily small mass ratios. In the two impurity limit for the heavier component they show that the pair forms a bound state for all charge combinations. In the lowest order approximation they derive a closed form expression Veff(r) for the binding potential which has short-range repulsion followed by attraction. In the classical limit, when the mass of embedded particles is large, m2 much greater than m, they can calculate from Veff(r) also the cohesive energy E and the bond length R of a metallic crystal such as lithium. The lowest order result is R = 3.1 A, E = {minus}0.9 eV, not entirely different from the experimental result for lithium metal. The same interaction for two holes on a parabolic band with m2 greater than m gives the quantum mechanical bound state which one may interpret as a boson or local pair in the case of high-Tc and heavy fermion superconductors. They also show that for compounds of the type YBa2Cu(3 - x)M(x)O(7 - delta) one can understand most of the experimental results for the superconducting and normal states with a single temperature dependent boson breaking function f(T) for each impurity content x governing the decay of bosons into pairing fermions. In the normal state f(T) turns out to be a linear, universal function, independent of the impurity content I and the oxygen content delta. They predict with universality a depression in Tc(x) with slight down bending in agreement with experiment. As a natural consequence of the model the bosons become localized slightly above Tc due to the Wigner crystallization, enhanced with lattice local field minima. The holes remain delocalized with a linearly increasing concentration in the normal state, thus explaining the rising Hall density. The boson localization temperature T(sub BL) shows up as a minimum in the Hall density R(sub ab)(exp -1).
- Research Organization:
- National Aeronautics and Space Administration, Houston, TX (United States). Lyndon B. Johnson Space Center
- OSTI ID:
- 135365
- Report Number(s):
- N-96-10230; NASA-CP-3290-VOL-1; S-792-VOL-1; NAS-1.55:3290-VOL-1; CONF-940627-; TRN: 9610262
- Resource Relation:
- Conference: 4. international conference and exhibition of the World Congress on Superconductivity, Orlando, FL (United States), 27 Jun - 1 Jul 1994; Other Information: PBD: Apr 1995; Related Information: Is Part Of Proceedings of the 4th International Conference and Exhibition: World Congress on Superconductivity, volume 1; Krishen, K.; Burnham, C.; PB: [10] p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Extraordinary behaviour of the Y[sub 1[minus]x]Pr[sub x]Ba[sub 2]Cu[sub 3]O[sub 7[minus][delta]] system
Resistivity and Hall effect of metallic oxygen-deficient YBa{sub 2}Cu{sub 3}O{sub {ital x}} films in the normal state