Eilers, FelixGrube, KaiZocco, Diego A.Wolf, ThomasMerz, MichaelSchweiss, PeterHeid, RolfEder, RobertYu, RongZhu, Jian-XinSi, QimiaoShibauchi, TakasadaLöhneysen, Hilbert v.2016-07-072016-07-072016Eilers, Felix, Grube, Kai, Zocco, Diego A., et al.. "Strain-Driven Approach to Quantum Criticality in AFe2As2 with A=K, Rb, and Cs." <i>Physical Review Letters,</i> 116, no. 23 (2016) American Physical Society: 237003. http://dx.doi.org/10.1103/PhysRevLett.116.237003.https://hdl.handle.net/1911/90838The iron-based superconductors AFe2As2 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.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttp://dx.doi.org/10.1103/PhysRevLett.116.237003