Single crystals of hexagonal structure Mn2P are synthesized by Sn flux for the first time.Transport and magnetic properties have been performed on the single crystals,which is an antiferromagnet with Neel temperature ...Single crystals of hexagonal structure Mn2P are synthesized by Sn flux for the first time.Transport and magnetic properties have been performed on the single crystals,which is an antiferromagnet with Neel temperature 103 K.Obvious anisotropy of resistivity is observed below the Neel temperature,which is manifested by metallic behavior with a current along the c-axis and semiconducting behavior with a current along the a-axis.The negative slope of temperature-dependent resistivity is observed above the Neel temperature in both a and c directions.Strong anisotropy of magnetic susceptibility is also evident from the magnetization measurements.A weak metamagnetic transition is observed only in a-axis plane at high magnetic field near 50–60 K compared to the c-axis.We believe these strong anisotropies of magnetic and transport properties are due to the anisotropy of spin arrangement.Mn2P could be a candidate for exploration of possible superconductivity due to the low spin state.展开更多
We report a^19F nuclear magnetic resonance(NMR)study on single-crystal KCa2 Fe4As4F2(Tc^33.3 K).The 19F NMR spectral shape of KCa2Fe4As4F2 is weakly dependent on temperature and the Knight shift is small,which implies...We report a^19F nuclear magnetic resonance(NMR)study on single-crystal KCa2 Fe4As4F2(Tc^33.3 K).The 19F NMR spectral shape of KCa2Fe4As4F2 is weakly dependent on temperature and the Knight shift is small,which implies weak coupling between the Ca F layer and the Fe As layer.The temperature dependence of 1/^19T1 shows a hump below Tc,however the 1/^75T1 decreases just below Tc,which implies that there are strong in-plane magnetic fluctuations in the Ca F layers than in the Fe As layers.This may be caused by the motion of vortices.The absence of the coherence peak suggests unconventional superconductivity in KCa2Fe4As4F2.展开更多
The physical properties of a solid are determined by the electrons near the Fermi energy and their low-lying excitations. Thus, it is crucially important to obtain the band structure near the Fermi energy of a materia...The physical properties of a solid are determined by the electrons near the Fermi energy and their low-lying excitations. Thus, it is crucially important to obtain the band structure near the Fermi energy of a material to understand many novel phenomena that occur, such as high-To superconductivity, density waves, and Dirac-type excitations. One important way to determine the Fermi surface topology of a material is from its quantum oscillations in an external magnetic field. In this article, we provide a brief introduction to the substation at the Synergetic Extreme Condition User Facility （SECUF）, with a focus on quantum oscillation measurements, including our motivation, the structure of and the challenges in building the substation, and perspectives.展开更多
基金Supported by the National Key Research and Development of China(Grant No.2017YFA0302901)the National Natural Science Foundation of China(Grant Nos.11674375,11634015 and 11921004)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33010100)the Postdoctoral Science Foundation of China.
文摘Single crystals of hexagonal structure Mn2P are synthesized by Sn flux for the first time.Transport and magnetic properties have been performed on the single crystals,which is an antiferromagnet with Neel temperature 103 K.Obvious anisotropy of resistivity is observed below the Neel temperature,which is manifested by metallic behavior with a current along the c-axis and semiconducting behavior with a current along the a-axis.The negative slope of temperature-dependent resistivity is observed above the Neel temperature in both a and c directions.Strong anisotropy of magnetic susceptibility is also evident from the magnetization measurements.A weak metamagnetic transition is observed only in a-axis plane at high magnetic field near 50–60 K compared to the c-axis.We believe these strong anisotropies of magnetic and transport properties are due to the anisotropy of spin arrangement.Mn2P could be a candidate for exploration of possible superconductivity due to the low spin state.
基金Supported by the National Key Research and Development Program of China under Grant No 2017YFA0302901the National Basic Research Program of China under Grant No 2015CB921304+1 种基金the National Science Foundation of China under Grant Nos11674375 and 11634015the Strategic Priority Research Program and Key Research Program of Frontier Sciences of the Chinese Academy of Sciences under Grant No XDB07020200
文摘We report a^19F nuclear magnetic resonance(NMR)study on single-crystal KCa2 Fe4As4F2(Tc^33.3 K).The 19F NMR spectral shape of KCa2Fe4As4F2 is weakly dependent on temperature and the Knight shift is small,which implies weak coupling between the Ca F layer and the Fe As layer.The temperature dependence of 1/^19T1 shows a hump below Tc,however the 1/^75T1 decreases just below Tc,which implies that there are strong in-plane magnetic fluctuations in the Ca F layers than in the Fe As layers.This may be caused by the motion of vortices.The absence of the coherence peak suggests unconventional superconductivity in KCa2Fe4As4F2.
文摘The physical properties of a solid are determined by the electrons near the Fermi energy and their low-lying excitations. Thus, it is crucially important to obtain the band structure near the Fermi energy of a material to understand many novel phenomena that occur, such as high-To superconductivity, density waves, and Dirac-type excitations. One important way to determine the Fermi surface topology of a material is from its quantum oscillations in an external magnetic field. In this article, we provide a brief introduction to the substation at the Synergetic Extreme Condition User Facility （SECUF）, with a focus on quantum oscillation measurements, including our motivation, the structure of and the challenges in building the substation, and perspectives.
