RSAVS superconductors: Materials with a superconducting state that is robust against large volume shrinkage

Huang, Cheng; Guo, Jing; Zhang, Jian-Feng; Stolze, K.; Cai, Shengbao; Liu, Kai; Weng, Hongming; Lu, Zhong-Yi; Wu, Qi; Xiang, Tao; Cava, R. J.; Sun, Liling

doi:10.1103/physrevmaterials.4.071801

Cited by 10 publications

(9 citation statements)

References 35 publications

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“…Surprisingly, the relationship between T c and pressure shows a roughly linear behavior and the increase is unsaturated up to the highest pressure in our measurement. In some alloys like NbTi and (ScZrNbTa) 0.6 (RhPd) 0.4 , the T c is robust against large volume shrinkage and shows a monotonous increase with pressure [33,38]. We believe that the situation in Cr 3 Ru may also share some similarity with them.…”

Section: Magnetization Hysteresis Loops and Vortex Propertiesmentioning

confidence: 81%

Comparative studies on superconductivity in Cr₃Ru compounds with bcc and A15 structures

Zhu

Zhang²,

Li³

et al. 2022

J. Phys.: Condens. Matter

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Chromium (Cr) is a transition metal element with 3d orbital electrons. In most compounds containing Cr, due to the correlation effect, twofold features, namely localization and itinerancy are expected. The localization gives rise to a magnetic moment, while the latter exhibits as the effective coherent weight for conductivity. Here we report the physical properties of Cr3Ru compounds with bcc and A15 structures by using multiple experimental tools. The resistivity measurements show sharp superconducting transitions at Tc = 2.77 K and Tc = 3.37 K for the bcc and A15 structures, respectively. A high residual resistivity exists in both phases. Magnetization measurements also show rather narrow superconducting transitions, with a clear hump feature in the intermediate temperature region (about 150 K), which may be ascribed to the remaining antiferromagnetic spin fluctuations. A pronounced second peak effect has been observed in magnetization hysteresis loops in the superconducting state only for samples with bcc structure. The specific heat coefficient reveals a clear jump at Tc. We find that s-wave gaps can be adopted to fit the low temperature specific heat data of both samples yielding ratios of 2Δ/kBTc about 3.6, indicating a moderate pairing strength. Interestingly, the Wilson ratios RW = Aχ0/γn are 3.81 and 3.62 for the bcc and A15 phases, suggesting a moderate correlation effect of conducting electron in the normal state. Besides, for samples with A15 structure, another specific heat anomaly occurs at about 0.85 K and is sensitive to magnetic fields. In addition, by applying high pressures, both system will exhibit an enhancement of Tc with a rate of about 0.019 K/GPa and 0.013 K/GPa for the bcc and A15 phases, respectively. Our combinatory results point to unusual behavior of both superconducting and normal states in these two Cr based alloys.

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Section: Magnetization Hysteresis Loops and Vortex Propertiesmentioning

confidence: 81%

Comparative studies on superconductivity in Cr₃Ru compounds with bcc and A15 structures

Zhu

Zhang²,

Li³

et al. 2022

J. Phys.: Condens. Matter

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“…Surprisingly, the relationship of T c and pressure shows a roughly linear behavior and the increase is unsaturated up to the highest pressure in our measurement. In some alloys like NbTi and (ScZrNbTa) 0.6 (RhPd) 0.4 , the T c is robust against large volume shrinkage and shows a monotonous increase with pressure [42,43]. In Fig.…”

Section: E Scanning Tunneling Spectrummentioning

confidence: 92%

Comparative studies on unconventional superconductivity in Cr$_3$Ru compounds with bcc and A15 structures

Zhu¹,

Zhang²,

Li³

et al. 2022

Preprint

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Chromium (Cr) is a transition metal element with 3d orbital electrons. In most compounds containing Cr, due to the correlation effect, twofold features of localization and itinerancy are expected. The localization gives rise to a magnetic moment, while the latter exhibits as the effective coherent weight for conductivity. Here we report the physical properties of Cr3Ru compounds with bcc or A15 structures by using multiple experimental tools. The resistivity measurements show sharp superconducting transitions at Tc = 2.77 K and Tc = 3.37 K for the bcc and A15 structures, respectively. A high residual resistivity exists for both samples with the mean-free-path in the scale of about 2 nm. Magnetization measurements also show rather narrow transitions, with a clear hump structure at high temperatures (Tc ≤ T ≤ 300 K), which may be ascribed to the remaining antiferromagnetic spin fluctuations. A pronounced second peak effect has been observed in magnetization hysteresis loops in the superconducting state only for samples with bcc structure. The specific heat coefficient reveals a clear jump at Tc. We find that s-wave gaps can be adopted to fit the low temperature specific heat data of both samples yielding ratios of about 2∆/kBTc ≈ 3.6, indicating a moderate pairing strength. Interestingly, the Wilson ratios RW = Aχ0/γn are 3.81 and 3.62 for the bcc and A15 phases, suggesting a moderate correlation effect of conducting electron in the normal state. Besides, for samples with A15 structure, another specific heat anomaly occurs at about 0.85 K and is sensitive to magnetic fields. By applying high pressures, both system will exhibit an enhancement of Tc with a rate of about 0.019 K/GPa and 0.013 K/GPa for the bcc and A15 phases, respectively. We also conduct tunneling spectrum measurements on these samples, and found that the coherence peaks are strongly smeared out with a gap in the scale of about 0.3 ∼ 0.5 meV. The strong suppression to the coherence peaks may be ascribed to the strong scattering seen from the resistivity measurements. Our combinatory results point to an unconventional superconductivity in these Cr based compounds.

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“…我们对铌钛合金超导体在超高压力下的晶体结构和常态输运性质等实验结果及超导电性进行了系统研究与分析 [42] , 发现其在 200 GPa压力范图 2 (a) 高熵合金(ScZrNbTa) 0.6 (RhPd) 0.4 在2.9-71.8 GPa压力范围内的电阻随温度变化关系; (b) 较低温度范围的归一化电阻; (c) 3.9-80.1 GPa压力范围X射线粉末衍射图谱; (d), (e) 晶格参数和晶胞体积随压力的变化 [41] Fig. 2.…”

Section: 在医疗、交通、能源、高能物理等领域都有广泛的应用unclassified

“…这类超导体在压力作用下, 即使发生了很大的体积压缩, 仍能保持T c 的不变. 我们最初在高熵合金的压力研究中发现了这种超导行为 [41] , 随后的研究表明广泛应用的商业化NbTi合金以及 Nb, Ta等简单金属元素也具有这种超导态 [42,43] . 特性与相应的物性 [44][45][46][47][48][49][50][51][52] .…”

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Discovery of robust superconductivity against volume shrinkage

Guo,

Wu,

Sun

2023

Acta Phys. Sin.

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The superconducting transition temperature (Tc) of superconductors are connected intimately with multiple degrees of freedom of charge, spin, orbital and lattice. Many studies have indicated that pressure is an effective way to tune Tc though change of crystal and electronic structures. Here, we report a new progress made in the high-pressure studies – discovery of a new type of superconductors whose Tc is robust against large volume shrinkage under extremely high pressure, named as RSAVS (Robust Superconductivity Against Volume Shrinkage) superconductors. Initially, such a RSAVS behavior was observed in the high entropy alloys of (TaNb)0.67(HfZrTi)0.33and (ScZrNbTa)0.6(RhPd)0.4, followed in the widely-used NbTi alloy, as well as Nb and Ta elements. Analysis shows that this type of superconductors possesses a body-centered cubic crystal structure and is composed of transition metal elements. The observed results not only present new research topics but also raise the question about what determines Tc in conventional or unconventional superconductors.

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RSAVS superconductors: Materials with a superconducting state that is robust against large volume shrinkage

Cited by 10 publications

References 35 publications

Comparative studies on superconductivity in Cr₃Ru compounds with bcc and A15 structures

Comparative studies on superconductivity in Cr₃Ru compounds with bcc and A15 structures

Comparative studies on unconventional superconductivity in Cr$_3$Ru compounds with bcc and A15 structures

Discovery of robust superconductivity against volume shrinkage

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RSAVS superconductors: Materials with a superconducting state that is robust against large volume shrinkage

Cited by 10 publications

References 35 publications

Comparative studies on superconductivity in Cr3Ru compounds with bcc and A15 structures

Comparative studies on superconductivity in Cr3Ru compounds with bcc and A15 structures

Comparative studies on unconventional superconductivity in Cr$_3$Ru compounds with bcc and A15 structures

Discovery of robust superconductivity against volume shrinkage

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Product

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Comparative studies on superconductivity in Cr₃Ru compounds with bcc and A15 structures

Comparative studies on superconductivity in Cr₃Ru compounds with bcc and A15 structures