Question Condensates

[Harry Costas]

Science does not break down.
Where did you get t=0. ?

 

[Harry Costas]

Condensate research is one of the most important fields to date.

[Submitted on 22 Jan 2025]

Magnetic phase diagram of cuprates and universal scaling laws​

Yves Noat, Alain Mauger, William Sacks

In this article we consider the magnetic field phase diagram of hole-doped high-Tc cuprates, which has been given much less attention than the temperature diagram. In the framework of the {\it pairon model}, we show that the two characteristic energies, the pair binding energy (the gap Δp) and the condensation energy (βc) resulting from pair correlations, give rise to two major magnetic fields, the upper critical field Bc2 and a second field, Bpg, associated with the pseudogap (PG). The latter implies a second length scale in addition to the coherence length, characteristic of incoherent pairs. Universal scaling laws for both Bc2 and Bpg are derived: Bc2 scales with the critical temperature, Bc2/Tc≃1.65 T/K, in agreement with many experiments, and Bpg has a similar scaling with respect to T∗. Finally, Fermi arcs centered on the nodal directions are predicted to appear as a function of magnetic field, an effect testable experimentally.

 

[Harry Costas]

For those who want to understand more and more, then keep on it.

[Submitted on 10 Feb 2025 (v1), last revised 16 Feb 2025 (this version, v2)]

Fermion mediated pairing in the Ruderman-Kittel-Kasuya-Yosida to Efimov transition regime​

Geyue Cai, Henry Ando, Sarah McCusker, Cheng Chin

The Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction and Efimov physics are two distinct quantum phenomena in condensed matter and nuclear physics, respectively. The RKKY interaction describes correlations between impurities mediated by an electron gas, while Efimov physics describes universal bound states of three particles with resonant interactions. Recently, both effects have been observed in Bose-Fermi mixtures in the weak and resonant interaction regimes, respectively. Intriguing conjectures exist to elucidate how the two phenomena meet in the transition regime where the mixture is strongly interacting. In this work, we explore the RKKY-Efimov transition in a mixture of bosonic Cs-133 and fermionic Li-6 near a tunable interspecies Feshbach resonance. From dispersion and relaxation measurements, we find that the transition is highlighted by a fermion-mediated scattering resonance between Cs atoms and a weaker resonance on Li atoms. These resonances represent reactive scattering of Cs and Li atoms in the many-body regime, which reduces to an Efimov resonance in the thermal gas regime. Our observation demonstrates the intriguing interplay of two-, three-, and many-body physics in an Bose-Fermi mixture that connects condensed matter physics, nuclear physics and quantum many-body chemistry.