The most popular nature publishes chenxianhui's la

2022-07-29
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Nature published chenxianhui's latest scientific research achievements on iron-based superconductors

chenxianhui's research group of the National Laboratory of Physical Sciences recently made important progress in the field of iron-based superconductors. The results show that it is very important to explore the interaction between lattice and spin degrees of freedom for understanding the mechanism of high temperature superconductivity. This achievement was published in the journal Nature on May 7 (nature 459, 64 (2009)). The above research work was completed in cooperation with wuziyu from the National Synchrotron Radiation Laboratory of the University of science and technology of China

recently, the superconductivity found in iron-based phosphorus compounds has broken through the McMillan limit (39K) predicted by the traditional BCS theory, setting off another upsurge of high-temperature superconductivity research. Theoretical studies show that the electron phonon interaction of the system can not explain such a high superconducting critical temperature, and a strong ferromagnetic/antiferromagnetic fluctuation mechanism is proposed. However, experiments show that the superconductivity and magnetism of iron-based superconductors are very sensitive to the crystal structure, which indicates that there may be unconventional electron phonon interaction in the system

chenxianhui's research group studied the changes of superconducting critical temperature (TC) and spin density wave transition temperature (TSDW) in smfeaso1 XFX and BA1 xkxfe2as2 systems through oxygen and iron isotope exchange, and found that the oxygen isotope effect of TC is very small, but the iron isotope effect is very large. Surprisingly, the iron isotope exchange in this system has the same effect on TC and TSDW. This shows that the electron phonon interaction plays a certain role in the superconducting mechanism, but it is not a simple electron phonon interaction mechanism, and there may be spin phonon coupling. In iron-based superconductors, the iron isotope effect of TC and SDW is greater than that of oxygen. This may be because the iron arsenic surface is a conductive surface, which has a great impact on superconductivity, and the spin density wave order also comes from the magnetic moment of iron. In copper oxide high temperature superconductors, the isotope effect of superconducting critical temperature is very sensitive with doping. At the optimum doping, the isotope effect almost disappears, but increases gradually with decreasing doping and reaches the maximum at the boundary between superconducting and antiferromagnetic states. This indicates that the isotope effect is also closely related to the magnetic fluctuation in copper oxygen high temperature superconductors. This anomalous isotope effect indicates that the electron phonon interaction is also very important in copper oxide compounds. Therefore, Professor chenxianhui's findings show that it is very important to understand the mechanism of high-temperature superconductivity to explore the interaction between lattice and spin degrees of freedom. The experimental force that the sample can withstand is as small as a few 10cn (such as spandex for textile)

since the discovery of high-temperature iron-based superconductor smfeas (O, f) system in 2008, chenxianhui research group has made a series of important progress in the research of iron-based high-temperature superconductors: it is the first in the world to prepare iron-based 122 single crystals by self-help solvent method; The electronic phase diagrams of iron-based superconductors with 1111 and 122 structures are systematically studied, and the changes with the physical properties of the doped system are studied. The experimental phenomenon of the coexistence of SDW and superconductivity in iron-based superconductors is proposed. At the same time, Professor chenxianhui has conducted extensive cooperation with well-known research groups at home and abroad, and achieved a series of results: through the study of Dreev reflection, the safety impact resistance of an can be judged according to its damage degree, it is found that iron-based superconductors generally have S-wave superconducting gap, and have the behavior of traditional BCS superconductors; adopt μ The meson spin confirms the coexistence of magnetic fluctuations and superconductivity in smfeaso1 XFX system; Apres experiments show that SDW and superconductor coexist in 122 system; The magnetic structures of 122 and 1111 systems were studied by neutron scattering; Direct observation of the flux lattice in the superconducting state of iron-based superconductors by STM

up to now, Professor chenxianhui's research group has brought confidence to extruder enterprises. In the research of iron-based superconductors, he has published 3 papers in nature, 1 paper in nature materials, 9 papers in Physical Review Letters, and J. am Chem. Soc. Published 1 paper. Among them, one paper published last year (nature 453761 (2008)) was one of the five papers published that year with the most citations

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