Crossover from two-dimensional to three-dimensional superconducting states in bismuth-based cuprate superconductor

Abstract

To decipher the mechanism of high temperature superconductivity, it is important to know how the superconducting pairing emerges from the unusual normal states of cuprate superconductors, including pseudogap, anomalous Fermi liquid and strange metal (SM). A long-standing issue under debate is how the superconducting pairing is formed and condensed in the SM phase because the superconducting transition temperature is the highest in this phase. Here, we report the first experimental observation of a pressure-induced crossover from two-to three-dimensional superconducting states in the optimally-doped Bi 2 Sr 2 CaCu 2 O 8+ bulk superconductor at a pressure above 2.8 GPa, through state-of-the-art in-situ high-pressure measurements of resistance, magnetoresistance and magnetic susceptibility. By analyzing the temperature dependence of resistance, we find that the two-dimensional (2D) superconducting transition exhibits a Berezinski-Kosterlitz-Thouless-like behavior. The emergence of this 2D superconducting transition provides direct and strong evidence that the SM state is predominantly 2D-like. This is important to a thorough understanding of the phase diagram of cuprate superconductors.

Discovery of Dome‐Shaped Superconducting Phase and Anisotropic Transport in a van der Waals Layered Candidate NbIrTe4 under Pressure

“…As the temperature is just lowered than 6.0 K, the resistance increases by almost 20% for current perpendicular to the ab-plane, while it decreases by over 10% for current flowing at the ab-plane. The anisotropic behavior here is similar to the anisotropic superconductivity observed in a Bi 2 Sr 2 CaCu 2 O 8 + 𝛿 bulk superconductor, [27] the KTaO 3 (111) interfaces, [28] and the 2D granular superconductors. [29] The bonding between the layers is mainly van der Waals forces, allowing NbIrTe 4 to behave as a stack of intrinsic Josephson junctions.…”

Quantum phase transition from superconducting to insulating-like state in a pressurized cuprate superconductor

“…A notably successful application of this strategy leads to the discoveries of important cuprate-and Fe-based superconductors 10,20,21 . Therefore, high-pressure studies on superconductivity can not only help the search for new superconductors but also provide a deeper understanding of the correlation between the superconducting state and its neighbouring normal or ground state [22][23][24][25][26] . To reveal how the superconducting state or non-superconducting state develops-a central issue for understanding the high-T c superconductivity in cuprates, we performed a series of high-pressure investigations by employing our newly developed state-of-the-art technique-combined in situ high-pressure measurements of the resistance and alternating current (a.c.) susceptibility for the same sample at the same pressure.…”

Oscillating paramagnetic Meissner effect and Berezinskii–Kosterlitz–Thouless transition in Bi2Sr2CaCu2O8+δ monolayer

“…The absence of oscillating PME in the temperature regime above the kink suggested it was not caused by disparate 𝑇 & 's of the surface layer and the buried ones. Instead, for a layered system with small interlayer coupling, the BKT transition should have two characteristic temperatures determined by 1/Λ(𝑇 *+, 7 ) = 𝑘𝑇 *+, 7 , where 𝑑 is the thickness of the monolayer and 𝑛 is the number of phase-independent layers 52,53 . 𝑛 = 1 corresponded to a lower transition where all the layers are Josephson-coupled and 𝑛 = 𝑡/𝑑 for a higher one where all the layers were independent.…”