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TT: Fachverband Tiefe Temperaturen

TT 59: Correlated Electrons: Quantum-Critical Phenomena - Experiments

TT 59.5: Vortrag

Donnerstag, 14. März 2013, 16:00–16:15, H6

Pressure- and Composition-Induced Structural Quantum Phase Transition in the Cubic Superconductor (Sr,Ca)₃Ir₄Sn₁₃ — •Swee K. Goh¹, Lina E. Klintberg¹, Patricia L. Alireza¹, Paul Saines², David Tompsett¹, Peter Logg¹, Jinhu Yang^3,4, Bin Chen^3,4, Kazuyoshi Yoshimura⁴, and Malte Grosche¹ — ¹Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom — ²Department of Materials Science and Metallurgy, University of Cambridge, United Kingdom — ³Department of Physics, Hangzhou Normal University, China — ⁴Department of Chemistry, Kyoto University, Japan

The quasi-skutterudite superconductor Sr₃Ir₄Sn₁₃ has been reexamined recently. In addition to a superconducting transition at T_c = 5 K, pronounced anomalies can be seen in magnetic susceptibility and resistivity at T^* = 147 K. Using single crystal x-ray diffraction, we identify T^* = 147 K as the temperature where the system undergoes a structural transition from a simple cubic parent structure (I-phase) to a superlattice variant (I’-phase) with a lattice parameter twice that of the I-phase. Applying physical pressure or chemical pressure (via the isoelectronic substitution of Ca for Sr) leads to a rapid suppression of T^* = 147 K and an enhancement of T_c. Furthermore, a quasi-linear temperature dependence of resistivity is observed at the pressure where T^* = 147 K extrapolates to 0 K, reminiscent of quantum critical phenomena on the border of magnetism. We argue that the pressure phase diagram of Sr₃Ir₄Sn₁₃ features a superlattice quantum critical point.