| CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
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Cooper Molecules: Second Pairing of Cooper Pairs in Gapless Superconductor CeCoIn$_5$ |
| Jiang Hong Man, Ze Cheng** |
School of Physics, Huazhong University of Science and Technology, Wuhan 430074
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| Cite this article: |
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Jiang Hong Man, Ze Cheng 2019 Chin. Phys. Lett. 36 107401 |
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Abstract We establish a quantum field theory of phase transitions in gapless superconductor CeCoIn$_5$. It is found that uniform Cooper pair gases with pure gradient interactions with negative coefficient can undergo a Bardeen–Cooper–Schrieffer (BCS) condensation below a critical temperature. In the BCS condensation state, bare Cooper pairs with opposite wave vectors are bound into Cooper molecules, and uncoupled bare Cooper pairs are transformed into a new kind of quasiparticle, i.e., the dressed particles. The Cooper molecule system is a condensate or a superfluid, and the dressed particle system is a normal fluid. The critical temperature is derived analytically. The critical temperature of the superconductor CeCoIn$_5$ is obtained to be $T_{\rm c}=2.289$ K, which approaches the experimental data. The transition from the BCS condensation state to the normal state is a first-order phase transition.
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Received: 27 June 2019
Published: 21 September 2019
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| Fund: Supported by the National Natural Science Foundation of China under Grant Nos 10174024 and 10474025. |
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