Coexisting Kondo hybridization and itinerant f-electron ferromagnetism in UGe2
Coexisting Kondo hybridization and itinerant f-electron ferromagnetism in UGe2
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DOI：
10.1103/physrevresearch.4.l022030
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发表时间：
2022-01
期刊：
影响因子：
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通讯作者：
I. Giannakis;Divyanshi Sar;J. Friedman;Chang‐Jong Kang;M. Janoschek;P. Das;E. Bauer;G. Kotliar;P. Aynajian
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文献类型：
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作者：
I. Giannakis;Divyanshi Sar;J. Friedman;Chang‐Jong Kang;M. Janoschek;P. Das;E. Bauer;G. Kotliar;P. Aynajian
近藤杂化在部分填充的f -电子系统中传递了大量的电子态，这些电子态急剧接近费米能，导致从超导到奇异电子序的各种不稳定性。UGe 2是一个5 f重费米子系统，在低于Tc ~ 52 K的二级跃迁和Tx ~ 32 K的交叉跃迁下，Kondo杂化被两个铁磁相的形成所打断.这两个铁磁相伴随着自旋三重态超导性，只出现在高压下的磁有序相内并持续存在。这两个铁磁相的起源以及它们如何在近藤晶格中形成仍然不清楚。使用扫描隧道显微镜和光谱，我们探测的空间电子状态的UGe 2作为温度的函数。我们发现一个近藤共振和尖锐的5 f -电子状态附近的化学势，形成在高温下，根据我们的密度泛函理论（DFT）+ Gutzwiller计算。当温度降低到Tc以下时，共振变窄，并最终在低于Tx时分裂，在费米能处倾倒巡回f电子光谱重量。我们的研究结果表明，斯通纳机制形成的高度极化的铁磁相低于T x本身设置的阶段，在高压下出现的非常规超导性。
Kondo hybridization in partially filled f -electron systems conveys significant amount of electronic states sharply near the Fermi energy leading to various instabilities from superconductivity to exotic electronic orders. UGe 2 is a 5 f heavy fermion system, where the Kondo hybridization is interrupted by the formation of two ferromagnetic phases below a 2 nd order transition T c ~ 52 K and a crossover transition T x ~ 32 K. These two ferromagnetic phases are concomitantly related to a spin-triplet superconductivity that only emerges and persists inside the magnetically ordered phase at high pressure. The origin of the two ferromagnetic phases and how they form within a Kondo-lattice remain ambiguous. Using scanning tunneling microscopy and spectroscopy, we probe the spatial electronic states in the UGe 2 as a function of temperature. We find a Kondo resonance and sharp 5 f -electron states near the chemical potential that form at high temperatures above T c in accordance with our density functional theory (DFT) + Gutzwiller calculations. As temperature is lowered below T c , the resonance narrows and eventually splits below T x dumping itinerant f -electron spectral weight right at the Fermi energy. Our findings suggest a Stoner mechanism forming the highly polarized ferromagnetic phase below T x that itself sets the stage for the emergence of unconventional superconductivity at high pressure.