物理学报2025，Vol.74Issue(13)：388-397,10.DOI:10.7498/aps.74.20250180
超导三元氢化物CaYH12电子及空穴掺杂调控的第一性原理研究
First-principles study of regulation of electron and hole doping in superconducting ternary hydride CaYH12
摘要
Abstract
In the past few decades,achieving room-temperature superconductivity has become an unremitting pursuit of scientists.Guided by the"chemical precompression"theory,hydrogen-rich compounds have emerged as the main candidates for high-temperature superconductors,positioning them at the forefront of superconducting materials research.Extensive computational studies have identified numerous binary hydrides with predicted superconducting transition temperatures(Tc)exceeding 200 K,such as CaH6,H3S,MgH6,YH6,YH9,YH10,and LaH10.Significantly,the high-Tc super-conductivities of H3S,LaH10,CaH6,YH6,YH9 have been experimentally confirmed.Compared with binary hydrides,ternary hydrides offer more diverse chemical compositions and structures,potentially leading to enhanced properties.Zhang et al.[Zhang Z,Cui T,Hutcheon M J,et al.2022 Phys.Rev.Lett.128 047001]theoretically designed a series of AXH8-type(A=Sc,Ca,Y,Sr,La,Ba;X=Be,B,Al)ternary hydrides with"fluorite-type"backbone,which were predicted to have high-Tc values under moderate pressure.Among those ternary hydrides,LaBeH8 has been experimentally confirmed to achieve a Tc value of 110 K at 80 GPa.The Tc values of ternary clathrate hydrides of Li2MgH16 and Li2NaH17 have been predicted to greatly exceed the room temperature,while the required stabilization pressures all exceeded 200 GPa.Xie et al.[Xie H,Duan D F,Shao Z J,et al.2019 J.Phys.Condens.Matter.31 245404]and Liang et al.[Liang X W,Bergara A,Wang L Y,et al.2019 Phys.Rev.B 99 100505(R)]independently predicted CaYH12 compounds with Pm(3)m and Fd(3)m space groups,both of which exhibited high-Tc above 200 K at about 200 GPa.Other ternary hydrides,such as La-B-H,K-B-H,La-Ce-H,and Y-Ce-H,have also been extensively investigated.At current stage,a major focus of superconducting hydrides is to achieve high-temperature superconductivity at lower pressures.In this study,taking Pm(3)m(CaYH12)as a representative,we systematically investigate the effects of electron and hole doping on the dynamical stability and superconductivity in ternary hydride by first-principal calculations.The Pm(3)m(CaYH12)exhibits a Tc value of 218 K at 200 GPa,which is consistent with that reported previously.When decompressing to below 180 GPa,imaginary phonons emerge.The analysis of doping simulations demonstrates that the electron doping exacerbates the softening of the imaginary phonons,whereas hole doping eliminates the imaginary frequencies.At the pressures of 130,100 and 70 GPa,the Pm(3)m(CaYH12)phase can be stabilized by hole doping at the concentrations of 0.9,0.8,and 1.1 e/cell,respectively.Further electron-phonon coupling calculations show that the Tc values of Pm3m(CaYH12)at 130,100 and 70 GPa are 194,209,and 194 K at the corresponding doping level,which are only 10-20 K less than the Tc at 200 GPa.At the pressure of 70 GPa,Tc slightly decreases to 189 K at a doping level of 1.2 e/cell,primarily due to the reduced ωlog compared with that in the case of 1.1 e/cell.And the enhanced λ at 1.2 e/cell is mainly contributed by the average electron-phonon coupling matrix element<I2>and average phonon frequency<ω2>1/2,rather than the electronic density of states at the Fermi level N(εF).These results indicate that hole doping represents a promising and effective strategy for optimizing the superconductivity of Pm(3)m(CaYH12)by maintaining high-Tc at low pressures.Our study paves an avenue for realizing high-temperature superconductors at low pressure.关键词
超导三元氢化物/第一性原理计算/空穴掺杂/稳定压力调控Key words
superconducting ternary hydride/first-principles calculations/hole doping/stabilization pressure regulation引用本文复制引用
林建华,崔佳浩,庄全..超导三元氢化物CaYH12电子及空穴掺杂调控的第一性原理研究[J].物理学报,2025,74(13):388-397,10.基金项目
国家自然科学基金(批准号:12264038,11904187)资助的课题. Project supported by the National Natural Science Foundation of China(Grant Nos.12264038,11904187). （批准号:12264038,11904187）
