Temperature dependent single-crystal x-ray diffraction (XRD) in transmission mode probing the bulk of the newly discovered K0.8Fe1.6Se2 superconductor (T-c = 31.8 K) using synchrotron radiation is reported. A clear evidence of intrinsic phase separation at 520 K between two competing phases, (i) a first majority magnetic phase with a ThCr2Si2-type tetragonal lattice modulated by the iron root 5 x root 5 vacancy ordering and (ii) a minority non-magnetic phase having an in-plane compressed lattice volume and a root 2 x root 2 weak superstructure, is reported. The XRD peaks due to the Fe vacancy root 5 x root 5 ordering in the majority phase disappear on increasing the temperature to 580 K, well above phase separation temperature, confirming the order-disorder phase transition. The intrinsic phase separation at 520 K between a competing first magnetic phase and a second non-magnetic phase in the normal phase both having lattice superstructures (that imply different Fermi surface topology reconstructions and charge densities) is assigned to a lattice-electronic instability of the K0.8Fe1.6Se2 system typical of a system tuned at a Lifshitz critical point of an electronic topological transition that gives a multigap superconductor tuned to a shape resonance.

Intrinsic phase separation in superconducting K0.8Fe1.6Se2 (T-c=31.8 K) single crystals / Ricci, Alessandro; Poccia, Nicola; Joseph, Boby; B., Joseph; Gianmichele, Arrighetti; Luisa, Barba; Plaisier, Jasper; J., Plaisier; Campi, Gaetano; Yoshikazu, Mizuguchi; Hiroyuki, Takeya; Yoshihiko, Takano; Saini, Naurang Lal; Bianconi, Antonio. - In: SUPERCONDUCTOR SCIENCE & TECHNOLOGY. - ISSN 0953-2048. - STAMPA. - 24:(2011), p. 082002. [10.1088/0953-2048/24/8/082002]

Intrinsic phase separation in superconducting K0.8Fe1.6Se2 (T-c=31.8 K) single crystals

RICCI, ALESSANDRO;POCCIA, NICOLA;CAMPI, GAETANO;SAINI, Naurang Lal;BIANCONI, Antonio
2011

Abstract

Temperature dependent single-crystal x-ray diffraction (XRD) in transmission mode probing the bulk of the newly discovered K0.8Fe1.6Se2 superconductor (T-c = 31.8 K) using synchrotron radiation is reported. A clear evidence of intrinsic phase separation at 520 K between two competing phases, (i) a first majority magnetic phase with a ThCr2Si2-type tetragonal lattice modulated by the iron root 5 x root 5 vacancy ordering and (ii) a minority non-magnetic phase having an in-plane compressed lattice volume and a root 2 x root 2 weak superstructure, is reported. The XRD peaks due to the Fe vacancy root 5 x root 5 ordering in the majority phase disappear on increasing the temperature to 580 K, well above phase separation temperature, confirming the order-disorder phase transition. The intrinsic phase separation at 520 K between a competing first magnetic phase and a second non-magnetic phase in the normal phase both having lattice superstructures (that imply different Fermi surface topology reconstructions and charge densities) is assigned to a lattice-electronic instability of the K0.8Fe1.6Se2 system typical of a system tuned at a Lifshitz critical point of an electronic topological transition that gives a multigap superconductor tuned to a shape resonance.
01 Pubblicazione su rivista::01a Articolo in rivista
Intrinsic phase separation in superconducting K0.8Fe1.6Se2 (T-c=31.8 K) single crystals / Ricci, Alessandro; Poccia, Nicola; Joseph, Boby; B., Joseph; Gianmichele, Arrighetti; Luisa, Barba; Plaisier, Jasper; J., Plaisier; Campi, Gaetano; Yoshikazu, Mizuguchi; Hiroyuki, Takeya; Yoshihiko, Takano; Saini, Naurang Lal; Bianconi, Antonio. - In: SUPERCONDUCTOR SCIENCE & TECHNOLOGY. - ISSN 0953-2048. - STAMPA. - 24:(2011), p. 082002. [10.1088/0953-2048/24/8/082002]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/478718
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