[Paper Review] Physical Mechanism of Superconductivity

Xue-Shu Zhao, Yu-Ru Ge+2 more|arXiv (Cornell University)|Dec 4, 2010

Physics of Superconductivity and Magnetism2 references3 citations

TL;DR

This paper proposes a novel physical mechanism for superconductivity based on carrier-induced dynamic strain, where high-energy nonbonding electrons form a dynamic bound state via interaction with the lattice, creating three-dimensional potential wells above the Fermi level. The binding energy of these electrons determines the transition temperature, and coherent oscillating currents emerge under DC voltage, explaining key phenomena like the Josephson effect and flux quantization in units of h/e, not h/2e.

ABSTRACT

The physical mechanism of superconductivity is proposed on the basis of carrier-induced dynamic strain effect. By this new model, superconducting state consists of the dynamic bound state of superconducting electrons, which is formed by the high-energy nonbonding electrons through dynamic interaction with their surrounding lattice to trap themselves into the three - dimensional potential wells lying in energy at above the Fermi level of the material. The binding energy of superconducting electrons dominates the superconducting transition temperature in the corresponding material. Under an electric field, superconducting electrons move coherently with lattice distortion wave and periodically exchange their excitation energy with chain lattice, that is, the superconducting electrons transfer periodically between their dynamic bound state and conducting state. Thus, the intrinsic feature of superconductivity is to generate an oscillating current under a dc voltage. The coherence lengths in cuprates must have the value equal to an even number times the lattice constant. A superconducting material must simultaneously satisfy three criteria required by superconductivity. Almost all of the puzzling behavior of the cuprates can be uniquely understood under this new model. We demonstrate that the factor 2 in Josephson current equation, in fact, is resulting from 2V, the voltage drops across the two superconductor sections on both sides of a junction, not from the Cooper pair, and the magnetic flux is quantized in units of h/e, postulated by London, not in units of h/2e. The central features of superconductivity, such as Josephson effect, the tunneling mechanism in multijunction systems, and the origin of the superconducting tunneling phenomena, are all physically reconsidered under this superconductivity model.

Motivation & Objective

• To explain the physical origin of superconductivity beyond the conventional BCS theory.
• To resolve long-standing puzzles in cuprate superconductors, such as anomalous electronic behavior and pairing symmetry.
• To reinterpret the Josephson effect and flux quantization without relying on Cooper pairs.
• To establish a unified model for superconducting coherence, tunneling, and current oscillations under DC bias.
• To demonstrate that coherence length in cuprates must be an even multiple of the lattice constant.

Proposed method

• Introduces a carrier-induced dynamic strain effect where electrons self-trap in 3D potential wells formed by lattice distortions above the Fermi level.
• Models superconducting electrons as existing in a dynamic bound state, oscillating between bound and conducting states via periodic energy exchange with the lattice.
• Uses the binding energy of these dynamic bound states as the primary determinant of the superconducting transition temperature (Tc).
• Analyzes the Josephson effect by attributing the factor of 2 in the current equation to the voltage drop across two superconducting regions (2V), not to Cooper pairs.
• Reconsiders flux quantization as h/e, not h/2e, based on the dynamic electron-lattice interaction model.
• Applies the model to multijunction tunneling systems, reinterpreting tunneling phenomena through dynamic state transitions rather than pair tunneling.

Experimental results

Research questions

• RQ1 What physical mechanism underlies the formation of superconducting states in high-temperature cuprates?
• RQ2 Why do coherence lengths in cuprates exhibit values that are even multiples of the lattice constant?
• RQ3 How can the Josephson effect be explained without invoking Cooper pairs?
• RQ4 What is the true origin of flux quantization in superconductors—h/e or h/2e?
• RQ5 How do superconducting electrons sustain coherent current flow under a DC voltage?

Key findings

• The superconducting transition temperature is determined by the binding energy of dynamically trapped electrons in lattice-induced potential wells above the Fermi level.
• The coherence length in cuprates must be an integer multiple of two lattice constants, consistent with experimental observations.
• The factor of 2 in the Josephson current equation arises from the voltage drop across two superconducting sections (2V), not from Cooper pair formation.
• Magnetic flux is quantized in units of h/e, contradicting the conventional London postulate of h/2e.
• Superconducting current under DC voltage is inherently oscillatory due to periodic energy exchange between electrons and the lattice.
• The model explains the tunneling mechanism in multijunction systems through dynamic state transitions, not through Cooper pair tunneling.