Magnetic materials with noncollinear spin configurations have engendered significant interest in condensed matter physics due to their intriguing physical properties.We direct our attention towards the magnetic proper...Magnetic materials with noncollinear spin configurations have engendered significant interest in condensed matter physics due to their intriguing physical properties.We direct our attention towards the magnetic properties and critical behavior of single-crystal SmMn_(2)Ge_(2),an itinerant magnet with numerous temperature-dependent magnetic phase transitions.Notably,SmMn_(2)Ge_(2)displays significant magnetic anisotropy with easy magnetization direction switching from the c axis to the ab plane as temperature decreases.The critical behavior of the ferromagnetic transition occurring above room temperature is thoroughly examined.Reliable and self-consistent critical exponents,includingβ=0.292(2),γ=0.924(8),andδ=4.164(6),along with the Curie temperature T_c=347 K,are extracted through various methods,which provide evidence for the coexistence of multiple magnetic interactions in SmMn_(2)Ge_(2).Further analysis reveals that the magnetic interaction of SmMn_(2)Ge_(2)is a long-range type with the interaction distance decaying as J(r)~r^(-4.35).展开更多
We report the magnetoresistance(MR),de Haas-van Alphen(dHvA) oscillations and the electronic structures of single-crystal PtGa.The large unsaturated MR is observed with the magnetic field B ‖ [111].Evident dHvA oscil...We report the magnetoresistance(MR),de Haas-van Alphen(dHvA) oscillations and the electronic structures of single-crystal PtGa.The large unsaturated MR is observed with the magnetic field B ‖ [111].Evident dHvA oscillations with the B ‖ [001] configuration are observed,from which twelve fundamental frequencies are extracted and the spin-orbit coupling(SOC) induced band splitting is revealed.The light cyclotron effective masses are extracted from the fitting by the thermal damping term of the Lifshitz-Kosevich formula.Combining with the calculated frequencies from the first-principles calculations,the dHvA frequencies F1/F3 and F11/F12are confirmed to originate from the electron pockets at F and R,respectively.The first-principles calculations also reveal the existence of spin-3/2 Rarita-Schwinger-Weyl fermions and time-reversal doubling of the spin-1 excitation at Γ and R with large Chern numbers of ±4 when SOC is included.展开更多
We conduct a detailed examination of the magnetic and electrical transport properties in GdAlSi and SmAlGe crystals,which possess a LaPtSi-type structure(space group I4_(1)md).The magnetic susceptibility data unambigu...We conduct a detailed examination of the magnetic and electrical transport properties in GdAlSi and SmAlGe crystals,which possess a LaPtSi-type structure(space group I4_(1)md).The magnetic susceptibility data unambiguously reveal magnetic ordering below a characteristic transition temperature(T_(N)).For GdAlSi,a hysteresis loop is observed in the magnetization and magnetoresistance curves within the ab plane when the magnetic field is applied below T_(N),which is around32 K.Notable specific heat anomalies are detected at 32 K for GdAlSi and 6 K for SmAlGe,confirming the occurrence of magnetic transitions.In addition,the extracted magnetic entropy at high temperatures is consistent with the theoretical value of Rln(2J+1) for J=7/2 in Gd^(3+) and J=5/2 in Sm^(3+),respectively.SmAlGe also exhibits Schottky-like specific heat contributions.Additionally,both GdAlSi and SmAlGe exhibit positive magnetoresistance and a normal Hall effect.展开更多
基金the National Natural Science Foundation of China(Grant Nos.12074425 and 11874422)the National Key R&D Program of China(Grant No.2019YFA0308602)。
文摘Magnetic materials with noncollinear spin configurations have engendered significant interest in condensed matter physics due to their intriguing physical properties.We direct our attention towards the magnetic properties and critical behavior of single-crystal SmMn_(2)Ge_(2),an itinerant magnet with numerous temperature-dependent magnetic phase transitions.Notably,SmMn_(2)Ge_(2)displays significant magnetic anisotropy with easy magnetization direction switching from the c axis to the ab plane as temperature decreases.The critical behavior of the ferromagnetic transition occurring above room temperature is thoroughly examined.Reliable and self-consistent critical exponents,includingβ=0.292(2),γ=0.924(8),andδ=4.164(6),along with the Curie temperature T_c=347 K,are extracted through various methods,which provide evidence for the coexistence of multiple magnetic interactions in SmMn_(2)Ge_(2).Further analysis reveals that the magnetic interaction of SmMn_(2)Ge_(2)is a long-range type with the interaction distance decaying as J(r)~r^(-4.35).
基金Supported by the National Key Research and Development Program of China(Grant Nos.2019YFA0308602, 2018YFA0305700 and 2016YFA0300600)the National Natural Science Foundation of China(Grant Nos.11874422 and 11574391)+6 种基金the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant Nos.19XNLG18 and 18 XNLG14)the Chinese Academy of Sciences(Grant No.XDB28000000)the Science Challenge Project(Grant No.TZ2016004)the K.C.Wong Education Foundation(Grant No.GJTD-2018-01)the Beijing Municipal Science&Technology Commission(Grant No.Z181100004218001)the Beijing Natural Science Foundation(Grant No.Z180008)
文摘We report the magnetoresistance(MR),de Haas-van Alphen(dHvA) oscillations and the electronic structures of single-crystal PtGa.The large unsaturated MR is observed with the magnetic field B ‖ [111].Evident dHvA oscillations with the B ‖ [001] configuration are observed,from which twelve fundamental frequencies are extracted and the spin-orbit coupling(SOC) induced band splitting is revealed.The light cyclotron effective masses are extracted from the fitting by the thermal damping term of the Lifshitz-Kosevich formula.Combining with the calculated frequencies from the first-principles calculations,the dHvA frequencies F1/F3 and F11/F12are confirmed to originate from the electron pockets at F and R,respectively.The first-principles calculations also reveal the existence of spin-3/2 Rarita-Schwinger-Weyl fermions and time-reversal doubling of the spin-1 excitation at Γ and R with large Chern numbers of ±4 when SOC is included.
基金supported by the National Natural Science Foundation of China(Grant No.12074425)the National Key R&D Program of China(Grant No.2019YFA0308602)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant No.23XNKJ22)。
文摘We conduct a detailed examination of the magnetic and electrical transport properties in GdAlSi and SmAlGe crystals,which possess a LaPtSi-type structure(space group I4_(1)md).The magnetic susceptibility data unambiguously reveal magnetic ordering below a characteristic transition temperature(T_(N)).For GdAlSi,a hysteresis loop is observed in the magnetization and magnetoresistance curves within the ab plane when the magnetic field is applied below T_(N),which is around32 K.Notable specific heat anomalies are detected at 32 K for GdAlSi and 6 K for SmAlGe,confirming the occurrence of magnetic transitions.In addition,the extracted magnetic entropy at high temperatures is consistent with the theoretical value of Rln(2J+1) for J=7/2 in Gd^(3+) and J=5/2 in Sm^(3+),respectively.SmAlGe also exhibits Schottky-like specific heat contributions.Additionally,both GdAlSi and SmAlGe exhibit positive magnetoresistance and a normal Hall effect.
