title: Enhancement of the critical temperature of HgBa₂CuO(4+δ) by applying uniaxial and hydrostatic pressure: implications for a universal trend in cuprate superconductors.
abstract: It is well known that the superconducting transition temperature (T(c)) of cuprate superconductors can be enhanced by varying certain structural and electronic parameters, such as the flatness of the CuO₂ planes or their doping level. We determine the uniaxial and hydrostatic pressure derivatives of T(c) in the structurally simple tetragonal compound HgBa₂CuO(4+δ) near optimal doping. Our results provide experimental evidence for two further methods to enhance T(c): (i) reducing the area of the CuO₂ planes, and (ii) increasing the separation of the CuO₂ planar groups. T(c) is found to couple much more strongly to the ratio c/a of the lattice constants than to the unit cell volume. A comparison with prior results for structurally more complicated cuprates reveals a general trend of uniaxial pressure derivatives with T(c).
authors.affiliation: Institute for Solid State Physics, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Hardy
authors.forename: N J
authors.initials: NJ
authors.lastname: Hillier
authors.forename: C
authors.initials: C
authors.lastname: Meingast
authors.forename: D
authors.initials: D
authors.lastname: Colson
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: N
authors.initials: N
authors.lastname: Barišić
authors.forename: G
authors.initials: G
authors.lastname: Yu
authors.forename: X
authors.initials: X
authors.lastname: Zhao
authors.forename: M
authors.initials: M
authors.lastname: Greven
authors.forename: J S
authors.initials: JS
authors.lastname: Schilling