We have successfully grown an arsenopyrite marcasite type RhSb2 single crystal, and systematically investigated its crystal structure, electrical transport, magnetic susceptibility, heat capacity, and thermodynamic pr...We have successfully grown an arsenopyrite marcasite type RhSb2 single crystal, and systematically investigated its crystal structure, electrical transport, magnetic susceptibility, heat capacity, and thermodynamic properties. We found that the temperature-dependent resistivity exhibits a bad metal behavior with a board peak around 200 K. The magnetic susceptibility of RhSb2 shows diamagnetism from 300 K to 2 K. The low-temperature specific heat shows a metallic behavior with a quite small electronic specific-heat coefficient. No phase transition is observed in both specific heat and magnetic susceptibility data. The Hall resistivity measurements show that the conduction carriers are dominated by electrons with ne = 8.62 × 10^(18) cm^(-3) at 2 K, and the electron carrier density increases rapidly above 200 K without change sign. Combining with ab-initio band structure calculations, we showed that the unusual peak around 200 K in resistivity is related to the distinct electronic structure of RhSb_2. In addition, a large thermopower S(T) about -140 μV/K is observed around 200 K, which might be useful for future thermoelectric applications.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
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674375,11634015,11925408,and 11674369)the National Basic Research Program of China(Grant Nos.2016YFA0300600,2016YFA030240,2017YFA0302901,and 2018YFA0305700)+4 种基金the Strategic Priority Research Program and Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(Grant Nos.QYZDB-SSW-SLH013,XDB28000000,and XXH13506-202)the Science Challenge Project of China(Grant No.TZ2016004)the K.C.Wong Education Foundation,China(Grant No.GJTD-2018-01)the Beijing Natural Science Foundation,China(Grant No.Z180008)the Beijing Municipal Science and Technology Commission,China(Grant No.Z181100004218001)。
文摘We have successfully grown an arsenopyrite marcasite type RhSb2 single crystal, and systematically investigated its crystal structure, electrical transport, magnetic susceptibility, heat capacity, and thermodynamic properties. We found that the temperature-dependent resistivity exhibits a bad metal behavior with a board peak around 200 K. The magnetic susceptibility of RhSb2 shows diamagnetism from 300 K to 2 K. The low-temperature specific heat shows a metallic behavior with a quite small electronic specific-heat coefficient. No phase transition is observed in both specific heat and magnetic susceptibility data. The Hall resistivity measurements show that the conduction carriers are dominated by electrons with ne = 8.62 × 10^(18) cm^(-3) at 2 K, and the electron carrier density increases rapidly above 200 K without change sign. Combining with ab-initio band structure calculations, we showed that the unusual peak around 200 K in resistivity is related to the distinct electronic structure of RhSb_2. In addition, a large thermopower S(T) about -140 μV/K is observed around 200 K, which might be useful for future thermoelectric applications.
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.
