Revealing the A1g-type strain effect on superconductivity and nematicity in FeSe thin flake

The driving mechanism of nematicity and its twist with superconductivity in iron-based superconductors are still under debate.Recently,a dominant B1g-type strain effect on superconductivity is observed in underdoped iron-pnictides superconductors Ba(Fe_(1-x)Co_(x))_(2)As_(2),suggesting a strong interplay between nematicity and superconductivity.Since the long-range spin order is absent in FeSe superconductor,whether a similar strain effect could be also observed or not is an interesting question.Here,by utilizing a flexible film as substrate,we successfully achieve a wide-range-strain tuning of FeSe thin flake,in which both the tensile and compressive strain could reach up to~0.7%,and systematically study the strain effect on both superconducting and nematic transition(T_(c)and Ts)in the FeSe thin flake.Our results reveal a predominant A1g-type strain effect on T_(c).Meanwhile,Ts exhibits a monotonic anti-correlation with T_(c)and the maximum T_(c)reaches to 12 K when Ts is strongly suppressed under the maximum compressive strain.Finally,in comparison with the results in the underdoped Ba(Fe_(1-x)Co_(x))_(2)As_(2),the absence of B1g-type strain effect in FeSe further supports the role of stripe-type spin fluctuations on superconductivity.In addition,our work also supports that the orbital degree of freedom plays a key role to drive the nematic transition in FeSe.

Precise Forecast and Application of Time Delay Receiving Schedule for a New Generation of Polar Orbit Meteorological Satellite

In order to finely predict the receiving schedule of the new generation of polar orbit meteorological satellite time-delay data and solve the problem of rapid positioning of lost data, this paper studies and proposes the satellite data recording and satellite program-controlled program, and designs the delay data receiving timeline precision forecasting method. It is concluded that the detection load of polar orbit meteorological satellite in our country has developed from single load to multiple loads, and the detection data need to be downloaded to the ground for processing and application. And as the satellite load increases and the accuracy of each payload detection and channel increases, the amount of probing data will further increase, which in turn will require further increase of the speed of data transmission in the earth. Due to the limitation of the space data transmission frequency band, under the prior art system, the increase of the satellite data transmission rate is limited. On the basis of understanding the working principle of Fengyun-3, the new transmission system will be implemented in terms of data source compression, channel coding, modulation and polarization multiplexing by exploring new weather transmission systems for meteorological satellites in the future upgrade and at the same time analyze ways to avoid inter-satellite interference in order to solve the contradiction between the increase of data volume and the resource of terrestrial data transmission in the existing system.

Electrical transport properties of Fe Se single crystal under high magnetic field

Understanding the normal electronic state is crucial for unveiling the mechanism of unconventional superconductivity(SC). In this paper, by applying a magnetic field of up to 37T on FeSe single crystals, we could reveal the normal-state transport properties after SC was completely suppressed. The normal-state resistivity exhibited a Fermi liquid behavior at low temperatures. Large orbital magnetoresistance(MR) was observed in the nematic state with H//c, whereas MR was negligible with H//ab. The magnitude of the orbital MR showed an unusual reduction, and Kohler’s rule was severely violated below 10-25 K;these were attributable to spin fluctuations. The results indicated that spin fluctuations played a paramount role in the normalstate transport properties of FeSe albeit the Fermi liquid nature was at low temperature.