title: Strain-Driven Approach to Quantum Criticality in AFe_{2}As_{2} with A=K, Rb, and Cs.
abstract: The iron-based superconductors AFe_{2}As_{2} with A=K, Rb, Cs exhibit large Sommerfeld coefficients approaching those of heavy-fermion systems. We have investigated the magnetostriction and thermal expansion of this series to shed light on this unusual behavior. Quantum oscillations of the magnetostriction allow identifying the band-specific quasiparticle masses which by far exceed the band-structure derived masses. The divergence of the Grüneisen ratio derived from thermal expansion indicates that with increasing volume along the series a quantum critical point is approached. The critical fluctuations responsible for the enhancement of the quasiparticle masses appear to weaken the superconducting state.
authors.affiliation: Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Eilers
authors.affiliation: Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Grube
authors.affiliation: Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.
authors.forename: Diego A
authors.initials: DA
authors.lastname: Zocco
authors.affiliation: Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wolf
authors.affiliation: Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Merz
authors.affiliation: Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schweiss
authors.affiliation: Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Heid
authors.affiliation: Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Eder
authors.affiliation: Department of Physics, Renmin University of China, Beijing 100872, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Yu
authors.affiliation: Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Jian-Xin
authors.initials: JX
authors.lastname: Zhu
authors.affiliation: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors.forename: Qimiao
authors.initials: Q
authors.lastname: Si
authors.affiliation: Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan.|Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Takasada
authors.initials: T
authors.lastname: Shibauchi
authors.affiliation: Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany.|Physikalisches Institut, Karlsruher Institut für Technologie, 76049 Karlsruhe, Germany.
authors.forename: Hilbert V
authors.initials: HV
authors.lastname: Löhneysen