Sweetpotato （Ipomoea batatas L. Lain.） ranks fifth among the most important food crops, after rice, wheat, maize and cas- sava, on a fresh-weight basis in developing countries （Scott and Maldonado, 1999）. Sweetpot...Sweetpotato （Ipomoea batatas L. Lain.） ranks fifth among the most important food crops, after rice, wheat, maize and cas- sava, on a fresh-weight basis in developing countries （Scott and Maldonado, 1999）. Sweetpotato cultivars have white, yellow, purple or orange flesh, but only orange-fleshed sweetpotato cultivars are the rich sources of β-carotene, which is the precursor of vitamin A （Failla et al., 2009）. Accordingly, the orange-fleshed sweetpotato is the main source of 6-carotene for the people in underdeveloped coun- tries in Africa and Southeast Asia. Unfortunately, theβ-caro- tene content in most sweetpotato cultivars is rather low and insufficient in meeting the normal demand of human physi- ology （Liao et al., 2008）. Hence, developing sweetpotato cultivars rich inβ-carotene will be most desirable in crop development.展开更多
We have studied the magnetic and electrical transport properties of epitaxial NiAs-type CrTe thin films grown on SrTiO3（111） substrates. Unlike rectangle hysteresis loops obtained from magnetic measurements, we have...We have studied the magnetic and electrical transport properties of epitaxial NiAs-type CrTe thin films grown on SrTiO3（111） substrates. Unlike rectangle hysteresis loops obtained from magnetic measurements, we have identified intriguing extra bump/dip features from anomalous Hall experiments on the films with thicknesses less than 12 nm. This observed Hall anomaly is phenomenologically consistent with the occurrence of a topological Hall effect （THE） in chiral magnets with a skyrmion phase. Furthermore, the THE contribution can be tuned by the film thickness, showing the key contribution of asymmetric interfaces in stabilizing N6el-type skyrmions. Our work demonstrates that a CrTe thin film on SrTiO3（111） substrates is a good material candidate for studying real-space topological transport.展开更多
Although many emerging new phenomena have been unraveled in two dimensional(2D)materials with long-range spin orderings,the usually low critical temperature in van der Waals(vdW)magnetic material has thus far hindered...Although many emerging new phenomena have been unraveled in two dimensional(2D)materials with long-range spin orderings,the usually low critical temperature in van der Waals(vdW)magnetic material has thus far hindered the related practical applications.Here,we show that ferromagnetism can hold above 300 K in a metallic phase of 1T-CrTe2 down to the ultra-thin limit.It thus makes CrTe2 so far the only known exfoliated ultra-thin vdW magnets with intrinsic long-range magnetic ordering above room temperature.An in-plane room-temperature negative anisotropic magnetoresistance(AMR)was obtained in ultra-thin CrTe2 devices,with a sign change in the AMR at lower temperature,with−0.6%and+5%at 300 and 10 K,respectively.Our findings provide insights into magnetism in ultra-thin CrTe2,expanding the vdW crystals toolbox for future room-temperature spintronic applications.展开更多
In this paper,we systematically investigated the structural and magnetic properties of CrTe by combining particle swarm optimization algorithm and first-principles calculations.By considering the electronic correlatio...In this paper,we systematically investigated the structural and magnetic properties of CrTe by combining particle swarm optimization algorithm and first-principles calculations.By considering the electronic correlation effect,we predicted the ground-state structure of CrTe to be NiAs-type(space group P63/mmc)structure at ambient pressure,consistent with the experimental observation.Moreover,we found two extra meta-stable Cmca and R3m structures which have negative formation enthalpy and stable phonon dispersion at ambient pressure.The Cmca structure is a layered antiferromagnetic metal.The cleaved energy of a single layer is 0.464 J/m^(2),indicating the possible synthesis of CrTe monolayer.The R3m structure is a ferromagnetic half-metal.When external pressure is applied,the ground-state structure of CrTe transitions from P63/mmc structure to R3m structure at a pressure of 34 GPa,then to Fm3m structure at 42 GPa.We thought these results help to motivate experimental studies of the CrTe compounds in the application of spintronics.展开更多
基金supported by the National High-tech R&D Program(863 Program)(Nos.2011AA10A206 and 2012AA101204-3)Program for New Century Excellent Talents in University(No.NCET-12-0930)+1 种基金Fundamental Research Funds for the Central Universities(No.XDJK2013A024)the earmarked fund for China Agriculture Research System (No.CARS-11-C-20)
文摘Sweetpotato （Ipomoea batatas L. Lain.） ranks fifth among the most important food crops, after rice, wheat, maize and cas- sava, on a fresh-weight basis in developing countries （Scott and Maldonado, 1999）. Sweetpotato cultivars have white, yellow, purple or orange flesh, but only orange-fleshed sweetpotato cultivars are the rich sources of β-carotene, which is the precursor of vitamin A （Failla et al., 2009）. Accordingly, the orange-fleshed sweetpotato is the main source of 6-carotene for the people in underdeveloped coun- tries in Africa and Southeast Asia. Unfortunately, theβ-caro- tene content in most sweetpotato cultivars is rather low and insufficient in meeting the normal demand of human physi- ology （Liao et al., 2008）. Hence, developing sweetpotato cultivars rich inβ-carotene will be most desirable in crop development.
文摘We have studied the magnetic and electrical transport properties of epitaxial NiAs-type CrTe thin films grown on SrTiO3（111） substrates. Unlike rectangle hysteresis loops obtained from magnetic measurements, we have identified intriguing extra bump/dip features from anomalous Hall experiments on the films with thicknesses less than 12 nm. This observed Hall anomaly is phenomenologically consistent with the occurrence of a topological Hall effect （THE） in chiral magnets with a skyrmion phase. Furthermore, the THE contribution can be tuned by the film thickness, showing the key contribution of asymmetric interfaces in stabilizing N6el-type skyrmions. Our work demonstrates that a CrTe thin film on SrTiO3（111） substrates is a good material candidate for studying real-space topological transport.
基金This work is supported by the National Key R&D Program of China(Nos.2019YFA0307800,2017YFA0206302,and 2017YFA0206200)the National Natural Science Foundation of China(NSFC)(Nos.11974357,U1932151,and 51627801)+4 种基金G.Y.and X.H.thank the financial supports from the National Natural Science Foundation of China(NSFC)(No.11874409)This work is supported by the National Natural Science Foundation of China(NSFC)(Nos.61574060,and 8206300210)T.Y.acknowledges supports from the Major Program of Aerospace Advanced Manufacturing Technology Research Foundation NSFC and CASC,China(No.U1537204)Z.H.acknowledges the support from the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices(No.KF201816)The authors appreciate the help of Dr.Binbin Jiang in obtaining the HAADF-STEM images.
文摘Although many emerging new phenomena have been unraveled in two dimensional(2D)materials with long-range spin orderings,the usually low critical temperature in van der Waals(vdW)magnetic material has thus far hindered the related practical applications.Here,we show that ferromagnetism can hold above 300 K in a metallic phase of 1T-CrTe2 down to the ultra-thin limit.It thus makes CrTe2 so far the only known exfoliated ultra-thin vdW magnets with intrinsic long-range magnetic ordering above room temperature.An in-plane room-temperature negative anisotropic magnetoresistance(AMR)was obtained in ultra-thin CrTe2 devices,with a sign change in the AMR at lower temperature,with−0.6%and+5%at 300 and 10 K,respectively.Our findings provide insights into magnetism in ultra-thin CrTe2,expanding the vdW crystals toolbox for future room-temperature spintronic applications.
基金This work was supported by the National Natural Science Foundation of China(Nos.11904312 and 11904313),the Project of Hebei Educational Department,China(Nos.ZD2018015 and QN2018012),the Natural Science Foundation of Hebei Province of China(No.A2020203027),the Doctor Foundation Project of Yanshan University(No.BL19008),and the Scientific Research Foundation of the Higher Education of Hebei Province,China(No.BJ2020015).The numerical calculations in this paper have been done on the supercomputing system in the High Performance Computing Center of Yanshan University.
文摘In this paper,we systematically investigated the structural and magnetic properties of CrTe by combining particle swarm optimization algorithm and first-principles calculations.By considering the electronic correlation effect,we predicted the ground-state structure of CrTe to be NiAs-type(space group P63/mmc)structure at ambient pressure,consistent with the experimental observation.Moreover,we found two extra meta-stable Cmca and R3m structures which have negative formation enthalpy and stable phonon dispersion at ambient pressure.The Cmca structure is a layered antiferromagnetic metal.The cleaved energy of a single layer is 0.464 J/m^(2),indicating the possible synthesis of CrTe monolayer.The R3m structure is a ferromagnetic half-metal.When external pressure is applied,the ground-state structure of CrTe transitions from P63/mmc structure to R3m structure at a pressure of 34 GPa,then to Fm3m structure at 42 GPa.We thought these results help to motivate experimental studies of the CrTe compounds in the application of spintronics.
