Pressure-Driven Structural Phase Transitions and Superconductivity of Ternary Hydride MgVH₆

Abstract

A systematic investigation of ternary hydride MgVH6 within the pressure range of 0–200 GPa has been performed by means of the particle swarm optimization algorithm and density functional theory. Results of an extensive structure search and full relaxation further indicate that three new phases, P21/m, C2/m, and Pmn21, appear successively with the increasing of pressure, which contain two first-order structural phase transitions from P21/m to C2/m about 32 GPa and from C2/m to Pmn21 about 93 GPa. Three phases are all metallic phases by analyzing their band structures and density of electronic states and are also dynamically and mechanically stable based on their phonon spectra and elastic properties. More importantly, the electron–phonon coupling calculation indicates that MgVH6 with Pmn21 symmetry is a promising superconductor with an estimated superconducting transition temperature of 27.6 K at 150 GPa, which is similar to the superconducting transition temperature of 35 K at 300 GPa of ternary hydride LaSH6 (Phys. Rev. B 2019, 100, 184502). Further analysis of the electron–phonon coupling mechanism shows that the superconductivity is mainly derived from the strong electron–phonon interaction of heavier transition metal V atoms.

Prediction of ternary superconducting YCH12 using a novel solid hydrogen source under high pressure

“…This indicates that the Y-d electrons play a significant role in superconductivity and Y atoms are activated in EPC through a charge transfer with H atoms. This mechanism is similar to the cases of Fe 2 SH 3 , 60 Ta-H, 61 Hf-B-H 53 and MgVH 6 , 62 but different from that of most high-temperature H-rich superconductors.…”

Superconducting ternary hydrides under high pressure

“…105 In contrast to MgGeH 6 , MgVH 6 with low symmetry is stable between 93 and 200 GPa, and has same H content (Figure 5c), similarly conspicuous van Hove singularity near the Fermi level, and even larger EPC constant (1.43 vs. 1.16), however its metallicity is almost completely dominated by the V d electrons, bringing about low-frequency phonon dominated EPC and low ω log . 106 Therefore, T c of MgGeH 6 is much higher than MgVH 6 (Figure 3c). These results demonstrate that strong H-dominated EPC is crucial for high-T c superconductivity.…”

“…MgGeH 6 (Figure 5b), lying on the convex hull at 200–300 GPa, shows H‐dominated metallicity and significant “flat band‐steep band” feature near the Fermi level, leading to strong EPC with 50% from H‐derived high frequency 105 . In contrast to MgGeH 6 , MgVH 6 with low symmetry is stable between 93 and 200 GPa, and has same H content (Figure 5c), similarly conspicuous van Hove singularity near the Fermi level, and even larger EPC constant (1.43 vs. 1.16), however its metallicity is almost completely dominated by the V d electrons, bringing about low‐frequency phonon dominated EPC and low ω log 106 . Therefore, T c of MgGeH 6 is much higher than MgVH 6 (Figure 3c).…”

The Correlation Analysis for New Media Internet Celebrity Economy in College Students’ Entrepreneurial Values and Entrepreneurial Behavior

“…Based on the planned behavior theory, self-efficacy theory and triadic reciprocal determinism, a theoretical model of the impact mechanism of college students’ entrepreneurial values on entrepreneurial behavior in the Internet celebrity economy environment is constructed ( Skaalvik, 2020 ; Black et al, 2021 ; Zheng et al, 2021 ; Figure 2 ).…”