Pressure-induced and Composition-induced Structural Quantum Phase   Transition in the Cubic Superconductor (Sr/Ca)_3Ir_4Sn_{13}
  We show that the quasi-skutterudite superconductor Sr_3Ir_4Sn_{13} undergoes a structural transition from a simple cubic parent structure, the I-phase, to a superlattice variant, the I'-phase, which has a lattice parameter twice that of the high temperature phase. We argue that the superlattice distortion is associated with a charge density wave transition of the conduction electron system and demonstrate that the superlattice transition temperature T* can be suppressed to zero by combining chemical and physical pressure. This enables the first comprehensive investigation of a superlattice quantum phase transition and its interplay with superconductivity in a cubic charge density wave system. 
Lina E. Klintberg, Swee K. Goh, Patricia L. Alireza, Paul J. Saines,   David A. Tompsett, Peter W. Logg, Jinhu Yang, Bin Che...
cond-mat.str-el cond-mat.supr-con