Theoretical predictions for measurable manifestations of the Q-ball mechanism of superconductivity..

on 24-th September 2025 at 11.00, Moscow time, ACTP will hold a seminar "Theoretical predictions for measurable manifestations of the Q-ball mechanism of superconductivity in the high-Tc cuprates" by Prof. Sergei I. Mukhin (NUST MISIS).

Abstract
Recently proposed quantum Q-ball mechanism of the pseudogap state and high- T c superconductivity in cuprates [1,2], was afterwards supported by comparison [3] with micro X-ray diffraction data in HgBa 2 CuO 4+y [4,5]. This work is dedicated to theoretical predictions for several measurable physical properties of superconducting cuprates that could serve as specific manifestations of Q- balls existence in the strange metal phase, that are so far considered as seemingly unrelated with each other. These features include, but not exhaust: diamagnetism above Tc, ‘hidden’ antiferromagnetic order, pseudogap and nematicity in electronic properties, anti-nodal and nodal regions in the Brillouin zone of doped cuprates, as well as T-linear behavior [6,7] of electrical resistivity, specific heat maximum close to T*, percolative nature of strange metal to bulk superconductivity transition, etc. This paper shows how the listed above features of high-Tc cuprates may arise from the mixed 1 st /2 nd order Q-ball phase transition [1,2] that happens at a temperature T* due to ‘post-Fröhlich’ mechanism of Cooper pairing via exchange with finite nontopological solitons of spin/charge density fluctuations called Q-balls [1,2,3,7]. Proposed theoretical approach is used for calculation of the electrical resistivity due to scattering electrons on the Q-balls ‘gas’.

References

1. Mukhin S.I. Euclidean Q-balls of fluctuating SDW/CDE in the ‘nested’ Hubbard model of high-T c superconductors as the origin of pseudogap and superconducting behaviors. Condens. Matter, 7, 31 (2022).

2. Mukhin S.I. Euclidean Q-balls of electronic spin/charge densities confining superconducting condensates as the origin of pseudogap and high-T c superconducting behaviors. Annals of Physics, 447, 169000 (2022).

3. Mukhin S.I. Possible manifestation of Q-ball mechanism of high-T c superconductivity in X-ray diffraction. Condens. Matter, 8, 16 (2023).

4. Campi G., Barba L., Zhigadlo N.D., Ivanov A.A., Menushenkov A.P., Bianconi A., Q-Balls in the Pseudogap Phase of Superconducting HgBa2CuO4+y. Condens. Matter 8, 15 (2023).

5. Campi G., Bianconi A., Poccia N., Bianconi G., Barba L., Arrighetti G., Innocenti D., Karpinski J., Zhigadlo N.D., Kazakov S.M., et al.Inhomogeneity of charge-density-wave order and quenched disorder in a high-Tc superconductor. Nature, 525, 359 (2015).

6. Barišić N., Li Y., Yu G., Zhao X., Dressel M., Smontara A., Greven M. Universal sheet resistance and revised phase diagram of the cuprate high-temperature superconductors.PNAS 110, 12235 (2013 ).

7. Mukhin S.I. Q-ball mechanism of electron transport properties of high-Tc superconductors, e-print arXiv:2504.09610v2 [cond-mat.supr-con] 24 Apr 2025.