Presentation Information
[PC4-05]A Possible Superconductive Mechanism for Hydrides under Extreme Pressure with Room Temperature Superconductivity from Size Effect
*Xiaozhi Hu1 (1. University of Western Australia (Australia))
Keywords:
Mechanism of High Temperature Superconductivity,Hydride,Electron Redistribution,Atom Deformation,Room Temperature Superconductivity,Size Effect
[Purpose]“What is the microscopic mechanism for high-temperature superconductivity?” is one of 125 questions for future Exploration and Discovery listed in Science 2021 [1]. It was commented in 2023 that “the fact that external pressure can enhance the maximum temperature of superconductivity Tc in excess of what can be achieved by chemistry has puzzled researchers for decades” [2]. This study intends to address these two questions and then to suggest a possible path for achieving the room temperature superconductivity based on a new Tc model.
[Method] The well-known Lennard Jones interatomic potential, as illustrated in Fig. 1(a), illustrates strong repulsive forces are generated within “overlapping atoms” under compression. But it did not specify what is the repulsive force and what generates the repulsion. Following the suggestion that atom deformation was possible if the pressure was higher than 10 GPa [5], it is assumed in this study that valence electron orbits are altered due to atom deformation under extreme pressure, leading to redistribution of the local electron density, as shown in Fig. 1 (b).
[Results]
[Consideration] Based on the hypothesis of atom-deformation-induced electron redistribution, as in Fig. 1(b),
it has been assumed [7] that Tc is proportional to P and inversely proportional to the atomic
number Z.
Tc ∝ P/Z or (Tc − T0) *Z = Sgap * (P-P0) (1)
The Tc*Z – P relations, based on Eq. (1), are shown in Fig. 2 (b). The highest Tc from nano-thickness
LaH10 [8] is around 260 K, then “yielding” occurred. The idealized bi-atom system without “yielding”
as illustrated in Fig. 2(c) should have Tc higher than 300 K. In principle, nano-thickness LaH10 between
atomic-thickness and micro-thickness can be produced to reach the room temperature below 300 K.
[Conclusion]Obvious size/thickness effects on Tc of cuprate B1223 and black phosphorus summarized from the
literature [7] show that 7 – 30% enhancement in Tc is possible. 7% increase from 260 K will yield Tc
around 5°C (a breakthrough already), and 15% increase from 260 K will generate Tc around 26°C.
These prospects are significant as the room temperature superconductivity has been considered as the
holy grail in physics.
[Method] The well-known Lennard Jones interatomic potential, as illustrated in Fig. 1(a), illustrates strong repulsive forces are generated within “overlapping atoms” under compression. But it did not specify what is the repulsive force and what generates the repulsion. Following the suggestion that atom deformation was possible if the pressure was higher than 10 GPa [5], it is assumed in this study that valence electron orbits are altered due to atom deformation under extreme pressure, leading to redistribution of the local electron density, as shown in Fig. 1 (b).
[Results]
[Consideration] Based on the hypothesis of atom-deformation-induced electron redistribution, as in Fig. 1(b),
it has been assumed [7] that Tc is proportional to P and inversely proportional to the atomic
number Z.
Tc ∝ P/Z or (Tc − T0) *Z = Sgap * (P-P0) (1)
The Tc*Z – P relations, based on Eq. (1), are shown in Fig. 2 (b). The highest Tc from nano-thickness
LaH10 [8] is around 260 K, then “yielding” occurred. The idealized bi-atom system without “yielding”
as illustrated in Fig. 2(c) should have Tc higher than 300 K. In principle, nano-thickness LaH10 between
atomic-thickness and micro-thickness can be produced to reach the room temperature below 300 K.
[Conclusion]Obvious size/thickness effects on Tc of cuprate B1223 and black phosphorus summarized from the
literature [7] show that 7 – 30% enhancement in Tc is possible. 7% increase from 260 K will yield Tc
around 5°C (a breakthrough already), and 15% increase from 260 K will generate Tc around 26°C.
These prospects are significant as the room temperature superconductivity has been considered as the
holy grail in physics.