报告摘要

Pressure-stabilized hydrides are a new rapidly growing class of high-temperature superconductors. Remarkable properties of H₃S (T_C = 200K), YH6 (T_C = 224K) and LaH₁₀ (T_C = 250K) at 130-200 GPa catalyzed the search for superconductivity in compressed ternary (X,Y)-H polyhydrides that can be obtained by pulsed laser heating of various alloys and intermetallics with hydrogen in diamond anvil cells. The uniquely high critical temperatures, upper critical magnetic fields and critical current densities of superhydrides are very attractive for the creation of new electronic devices based on high-pressure diamond anvil cells.

Lanthanum superhydride is a superconducting polyhydride with the highest critical temperature (T_С ≈ 250K) among known compounds. For this reason, the La-H system is one of the most attractive objects for solid-state NMR research. We studied the formation of La polyhydrides at pressures up to 165 GPa in a temperature range from 5 to 300K using¹³⁹La and¹H NMR technique. In my talk, I will pay special attention to calibration experiments, detection of the hydrogen background signal, and comparative ¹H NMR studies of Ce (T_C ≈ 80K in 7 T field) and La (T_C ≈ 230K in 7 T field) superhydrides. As we will see, the main focus in ¹H NMR of superhydrides must be on measuring relaxation times, which sometimes takes several weeks of machine time.

My report will also be devoted to modern trends in the field of hydride chemistry and superconductivity at high pressure. I will talk about recent results related to superconductivity in La-Sc-H and La-Ce-H ternary systems, including studies in strong pulsed magnetic fields up to 68 Tesla. Hall effect, SQUID and diode effects, X-ray diffraction data and magnetoresistance of these ternary compounds will be discussed.

个人简介

Dr Dmitrii Semenok, an advanced postdoctoral fellow of HPSTAR Beijing, received his Ph.D. degree in 2022 from Skolkovo Institute of Science and Technology (Moscow, Russia) under the supervision of Prof. Artem Oganov. He received two MSc degrees from Moscow Institute of Physics and Technology (MIPT) and Skoltech in 2018 after defending his master's thesis on computer modelling of superconducting hydrides of transition metals, lanthanides and actinides under high pressure. Dmitrii has participated in discoveries of many metal polyhydrides known today, including ThH₁₀, YH₆, CeH₉, PrH₉, NdH₉, EuH₉, BaH₁₂, SrH₂₂, SnH₄, La₄H₂₃, (La, Y)H₁₀, (La, Nd)H₁₀, (La, Ce)H₁₀, CsH₇, RbH₉ etc.

联系人：邓正，孔盼盼，靳常青

联系电话：82648041

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