Two-dimensional(2D)van der Waals material is a focus of research for its widespread application in optoelectronics,memories,and spintronics.The ternary compound Nb_(2)SiTe_(4) is a van der Waals semiconductor with exc...Two-dimensional(2D)van der Waals material is a focus of research for its widespread application in optoelectronics,memories,and spintronics.The ternary compound Nb_(2)SiTe_(4) is a van der Waals semiconductor with excellent air stability and small cleavage energy,which is suitable for preparing a few layers counterpart to explore novel properties.Here,properties of bulk Nb_(2)SiTe_(4) with large in-plane electrical anisotropy are demonstrated.It is found that hole carriers dominate at a temperature above 45 K with a carrier active energy of 31.3 meV.The carrier mobility measured at 100 K is about 213 cm^(2)·V^(-1)·s^(-1) in bulk Nb_(2)SiTe_(4),higher than the reported results.In a thin flake Nb_(2)SiTe_(4),the resistivity ratio between the crystalline axes of a and b is reaching about 47.3 at 2.5 K,indicating that there exists a large anisotropic transport behavior in their basal plane.These novel transport properties provide accurate information for modulating or utilizing Nb_(2)SiTe_(4) for electronic device applications.展开更多
Using the newly-developed solid ionic gating technique,we measure the electrical transport property of a thinflake NbSe2 superconductor(Tc=6.67 K)under continuous Li intercalation and electron doping.It is found that ...Using the newly-developed solid ionic gating technique,we measure the electrical transport property of a thinflake NbSe2 superconductor(Tc=6.67 K)under continuous Li intercalation and electron doping.It is found that the charge-density-wave transition is suppressed,while at the same time a carrier density,decreasing from7×10^14 cm^-2 to 2×10^14 cm^-2 also occurs.This tunable capability in relation to carrier density is 70%,which is 5 times larger than that found using the liquid ionic gating method[Phys.Rev.Lett.117(2016)106801].Meanwhile,we find that the scattering type of conduction electrons transits to the s-d process,which may be caused by the change of the occupied states of 4 d-electrons in Nb under the condition of Li intercalation.Simultaneously,we observe a certain decrement of electron-phonon coupling(EPC),based on the electron-phonon scattering model,in the high temperature range.Based on data gathered from in situ measurements,we construct a full phase diagram of carrier density,EPC and Tc in the intercalated NbSe2 sample,and qualitatively explain the variation of Tc within the BCS framework.It is our opinion that the in situ solid ionic gating method provides a direct route to describing the relationship between carrier density and superconductivity,which is helpful in promoting a clearer understanding of electronic phase competition in transition metal dichalcogenides.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFE0202600,2016YFA0300600,and 2017YFA0304700)by the National Natural Science Foundation of China(Grant Nos.51922105,51772322,and 11704401)Beijing Natural Science Foundation(Grant No.Z200005).
文摘Two-dimensional(2D)van der Waals material is a focus of research for its widespread application in optoelectronics,memories,and spintronics.The ternary compound Nb_(2)SiTe_(4) is a van der Waals semiconductor with excellent air stability and small cleavage energy,which is suitable for preparing a few layers counterpart to explore novel properties.Here,properties of bulk Nb_(2)SiTe_(4) with large in-plane electrical anisotropy are demonstrated.It is found that hole carriers dominate at a temperature above 45 K with a carrier active energy of 31.3 meV.The carrier mobility measured at 100 K is about 213 cm^(2)·V^(-1)·s^(-1) in bulk Nb_(2)SiTe_(4),higher than the reported results.In a thin flake Nb_(2)SiTe_(4),the resistivity ratio between the crystalline axes of a and b is reaching about 47.3 at 2.5 K,indicating that there exists a large anisotropic transport behavior in their basal plane.These novel transport properties provide accurate information for modulating or utilizing Nb_(2)SiTe_(4) for electronic device applications.
基金Supported by the Mo ST-Strategic International Cooperation in Science,Technology and Innovation Key Program(Grant No.2018YFE0202601)the National Key Research and Development Program of China(Grant Nos.2017YFA0304700 and2016YFA0300600)+1 种基金the National Natural Science Foundation of China(Grant Nos.51922105 and 51772322)the Chinese Academy of Sciences(Grant No.QYZDJ-SSW-SLH013)。
文摘Using the newly-developed solid ionic gating technique,we measure the electrical transport property of a thinflake NbSe2 superconductor(Tc=6.67 K)under continuous Li intercalation and electron doping.It is found that the charge-density-wave transition is suppressed,while at the same time a carrier density,decreasing from7×10^14 cm^-2 to 2×10^14 cm^-2 also occurs.This tunable capability in relation to carrier density is 70%,which is 5 times larger than that found using the liquid ionic gating method[Phys.Rev.Lett.117(2016)106801].Meanwhile,we find that the scattering type of conduction electrons transits to the s-d process,which may be caused by the change of the occupied states of 4 d-electrons in Nb under the condition of Li intercalation.Simultaneously,we observe a certain decrement of electron-phonon coupling(EPC),based on the electron-phonon scattering model,in the high temperature range.Based on data gathered from in situ measurements,we construct a full phase diagram of carrier density,EPC and Tc in the intercalated NbSe2 sample,and qualitatively explain the variation of Tc within the BCS framework.It is our opinion that the in situ solid ionic gating method provides a direct route to describing the relationship between carrier density and superconductivity,which is helpful in promoting a clearer understanding of electronic phase competition in transition metal dichalcogenides.
