Evidence for Pseudogap Phase in Cerium Superhydrides: CeH$_{10}$ and CeH$_9$

Dmitrii Semenok; Jianning Guo; Di Zhou; Wuhao Chen; Toni Helm; Alexander Kvashnin; Andrei Sadakov; Oleg Sobolevsky; Vladimir Pudalov; Chuanying Xi; Xiaoli Huang; Ivan Troyan

arXiv · 2307.11742

Evidence for Pseudogap Phase in Cerium Superhydrides: CeH$_{10}$ and CeH$_9$

Dmitrii Semenok·Jianning Guo·Di Zhou·Wuhao Chen·Toni Helm·Alexander Kvashnin·Andrei Sadakov·Oleg Sobolevsky·Vladimir Pudalov·Chuanying Xi·Xiaoli Huang·Ivan Troyan

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Abstract

Polyhydride superconductors have been shown to possess metallic properties with a Bardeen-Cooper-Schrieffer-type superconducting ground state. Here, we provide evidence for unconventional transport associated with a pseudogap phase in cubic cerium superhydride CeH$_{10}$ ($\textit{T}$$_C$ = 116 K) at pressure of 115-125 GPa. A large negative magnetoresistance in the non-superconducting state below 90 K, quasi $\textit{T}$-linear electrical resistance, and a sign-change of its temperature dependence mark the emergence of this phase. We studied the magnetic phase diagrams and the upper critical fields $\textit{B}$$_{C2}$(T) of CeH$_{10}$, CeH$_9$, and CeD$_9$ in pulsed fields up to 70 T. $\textit{B}$$_{C2}$(T) of CeH$_9$ and CeD$_9$ exhibits pronounced saturation at low temperatures in accordance with the Werthamer-Helfand-Hohenberg model, whereas CeH$_{10}$ stands out in particular, as it does not obey this model. Our observations, therefore, reveal the unconventional nature of non-superconducting state of cerium superhydride CeH$_{10}$.

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Dmitrii Semenok, Jianning Guo, Di Zhou, Wuhao Chen, Toni Helm, Alexander Kvashnin, Andrei Sadakov, Oleg Sobolevsky, Vladimir Pudalov, Chuanying Xi, Xiaoli Huang, Ivan Troyan. 2023-07-21. Evidence for Pseudogap Phase in Cerium Superhydrides: CeH$_{10}$ and CeH$_9$. https://arxiv.org/abs/2307.11742

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